Read the following passage and questions, then choose the right answer from options, the answer should be one of A, B, C, D.

<passage>:
Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] It has happened a hundred times in the long history of Earth—and, sooner or later, will happen again! Everyone—all the geologists, at any rate—had known about the Kiowa all even the professionals were interested in knowing. There was never so much as a landslide to bring the Fault to the attention of the It is not really surprising that it took so long to figure out the connection. The population of the states affected was in places as low as five people per square mile! The land was so dry it seemed anything is news in late August. And the geologists became interested. Seismologists were reporting unusual activity in the area, tremors too severe to be rock slides. Volcanic activity? Specifically, headlines, and some papers even left off the question mark. It may seem odd that the simplest explanation was practically not Edison were shaken to pieces by incredible earthquakes, whole bus- and for their university and government department to approve budgets. They found, of course, that Schwartzberg had been perfectly correct. They found themselves on the scene of what was fast becoming the most violent and widespread earthquake North America—probably the world—has ever seen in historic times. To describe it in the simplest terms, land east of the Fault was settling, and at a precipitous rate. buckling and dropping, the earth trembled downward. Atop the new There the devastation was even more thorough, if less spectacular. Dry earth churned like mud, and rock shards weighing tons bumped and rolled about like pebbles as they shivered and cracked into pebbles themselves. "It looks like sand dancing in a child's sieve," said the scene of disaster. "No one here has ever seen anything like it." And several small tremors everywhere east of the Fault, to almost twenty miles away, the now-familiar lurch and steady fall had already sent several thousand Coloradans scurrying for safety. the danger of rock slides from minor quakes. The geologists went home As the Fault moved north and south, new areas quivered into unwelcome life. Fields and whole mountainsides moved with deceptive sloth down, down. They danced "like sand in a sieve" dry, they boiled into rubble. Telephone lines, railroad tracks, roads snapped and simply disappeared. Virtually all east-west land communication was suspended and the President declared a national emergency. By 23 September the Fault was active well into Wyoming on the north, Tremendous fissures opened up perpendicular to the Fault, and a general The western borders of these states, and soon of the Dakotas and Oklahoma as well, were slowly sinking. On the actual scene of the disaster (or the scenes it is impossible to speak of anything this size in the singular) there was a horrifying confusion. Prairie and hill cracked open under intolerable strains as the land shuddered downward in gasps and leaps. Springs burst to the surface in hot geysers and explosions of steam. The downtown section of North Platte, Nebraska, dropped eight feet, just like that, on the afternoon of 4 October. "We must remain calm," floods, in the usual sense. The water moved too slowly, spread itself with no real direction or force. But the vast sheets of sluggish water and jelly-like mud formed death-traps for the countless refugees now 193 people had died in that one cave-in. Certainly by 7 October it had to be officially admitted that there was an exodus of epic proportion. Nearly two million people were on the move, and the U. S. was faced with a gigantic wave of refugees. Rails, roads and air-lanes were jammed with terrified hordes who had left everything behind to crowd eastward. an American Airlines plane was wrecked by a mob of would-be passengers in Bismarck, North Dakota. Federal and State troops were called out, but moving two million people was not to be done in an orderly way. autumn sunshine, growing higher as the land beneath them continued its inexorable descent. On 21 October, at Lubbock, Texas, there was a noise variously described as a hollow roar, a shriek and a deep musical vibration like a church bell. It was simply the tortured rock of the substrata giving way. The second phase of the national disaster was beginning. wanted to be somewhere else." Everyone in doomed Biloxi would have done well to have been somewhere else that evening. At approximately 8:30 p.m. the town shuddered, seemed to rise a little like the edge of a hall carpet caught in a draft, and sank. So did the entire Mississippi and Alabama coast, at about the same moment. The tidal wave which was to gouge the center from the U. S. marched on the land. From the north shore of Lake Ponchartrain to the Appalachicola River Mobile, Pensacola, Panama City: 200 miles of shoreline vanished, with over two and a half million people. An hour later a wall of water had swept over every town from Dothan, Alabama, to Bogalusa on the Louisiana-Mississippi border. of the gallant southland have faced and withstood invasion before." Then, as ominous creakings and groanings of the earth announced the approach of the tidal wave, he flew out of Montgomery half an hour before the town disappeared forever. One head of the wave plunged north, eventually to spend itself in Despite hopeful announcements that the wave was slowing, had virtually stopped after inundating Oklahoma City, was being swallowed up in the Lubbock, Texas, went under. On a curling reflex the tidal wave blotted out Sweetwater and Big Spring. The Texas panhandle disappeared in one great swirl. Whirlpools opened. A great welter of smashed wood and human debris was rescuers on the cliffs along what had been the west bank of the Pecos River afterwards recalled the hiss and scream like tearing silk as the water broke furiously on the newly exposed rock. It was the most terrible sound they had ever heard. "We couldn't hear any shouts, of course, not that far away and with all were people down there. When the water hit the cliffs, it was like a collision between two solid bodies. We couldn't see for over an hour, because of the spray." along the line of the original Fault. Irresistible fingers closed on Sterling, Colorado, on Sidney, Nebraska, on Hot Springs, South Dakota. The entire tier of states settled, from south to north, down to its flushes never came out right. Jimanettly, we'd left the king of hearts behind, in the rush!" But such lightheartedness and such happy endings were by no means typical. The world could only watch aghast as the water raced north under the shadow of the cliffs which occasionally crumbled, roaring, into the roaring waves. Day by day the relentless rush swallowed what had been dusty farmland, cities and towns. almost the entirety of eight states, and portions of twelve others, had simply vanished from the heart of the North American continent forever. It was in such a cataclysmic birth that the now-peaceful Nebraska Sea came to America. Today, nearly one hundred years after the unprecedented—and happily unrepeated—disaster, it is hard to remember the terror and despair of those weeks in October and November, 1973. It is inconceivable to think of the United States without its beautiful and economically essential it graduates from the warm waters of the Gulf of Mexico through the equally blue waves of the Mississippi Bight, becoming cooler and Unimaginable too would have been the general growth of population in the states surrounding the new sea. As the water tables rose and manufacturing and trade moved in to take advantage of the just-created axis of world communication, a population explosion was touched off of which we are only now seeing the diminution. This new westering is to be ranked with the first surge of pioneers which created the American

<question>:
What is most significant about the earthquake that happens?

<options>:
A It proved that the dust volcano was alive.
B It proved Schwartzberg's theory?
C It became a national tragedy, affecting most of the country.
D It happened quickly and suddenly.

<answer>:

C