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

<passage>:
Grannie Annie, who wrote science fiction under the nom de plume of Annabella C. Flowers, had stumbled onto a murderous plot more hair-raising than any she had ever concocted. And the danger from the villain of the piece didn't worry her—I was the guy he was shooting at. Extensive research did not uncover any evidence that voyage. The rule that no females could pass its portals was strictly ? What happened to the book you were hat, as modern as an atomic motor. She had probably written more drivel in the name of science fiction than anyone alive. But the public loved it. They ate up her stories, and they clamored for more. Her annual income totaled into six figures, and her publishers sat back and massaged their digits, watching their earnings mount. One thing you had to admit about her books. They may have been dime expeditions on Callisto, she went to Callisto. She was the most completely delightful crackpot I had ever known. "What happened to "It wasn't Guns , it was and it wasn't Ganymede , it was Pluto ." I grinned. "All complete, I'll bet, with threats against the universe and beautiful Earth heroines dragged in by the hair." your hero fall in love with a bug-eyed monster." NINE GENIUSES THE QUESTION PROGRAM OF THE SYSTEM "That damned fossilized dynamo," I muttered. "She'll be the death of me audience. When it had voice echoed through the theater: " And so it went. Questions from Mars, from Earth, from Saturn flowed in bantering side play, the experts gave their answers. When they failed, or when the Truthicator flashed a red light, he announced the name of the winner. brought me here. And then I began to notice things. seemed to have lost much of its original fervor. They applauded as before but they did so only at the signal of Doctor Universe. The spell created by the man was complete. Pompous and erect, he strode back and forth across the stage like a general surveying his army. His black eyes gleamed, and his thin lips A yellow-faced Kagor from the upper Martian desert country shuffled by, dragging his cumbersome third leg behind him. Kagors, of course, had an the Red Planet. But the thing that happened there was a throw back to Someone shouted, "Yah, yellow-face! Down with all Kagors!" As one rushed out and scattered the crowd. But a few stragglers lingered to shout derisive epithets. was all but deserted. "The I.P. men aren't strong enough." The old woman paused. "Did you ever hear of the Green Flames?" she "It's not a new kind of anything. The Green Flame is a radio-active to radium in that they consist of streams of material particles projected at high speed. But the character of the Gamma never been completely analyzed. Like those set up by radium, they are electromagnetic pulsations, but they are also a strange combination of Beta or cathode rays with negatively charged electrons. Gamma rays from the Green Flame rock, they produce in the creature's brain a certain lassitude and lack of energy. As the period of exposure increases, this condition develops into a sense of impotence and a desire for leadership or guidance. Occasionally, as with the weak-willed, there is a spirit of intolerance. The Green Flames might be said to be an inorganic opiate, a thousand times more subtle and more powerful than any known drug." I was sitting up now, hanging on to the woman's every word. "Now in 2710, as you'd know if you studied your history, the three planets of Earth, Venus, and Mars were under governmental bondage. The cruel dictatorship of Vennox I was short-lived, but it lasted long enough to endanger all civilized life. "The archives tell us that one of the first acts of the overthrowing government was to cast out all Green Flames, two of which Vennox had ordered must be kept in each household. The effect on the people was immediate. Representative government, individual enterprise, freedom Grannie Annie lit a cigarette and flipped the match to the floor. an old space ship. The hold of that space ship was packed with Green Flames!" I said, "So what?" if it were true? Green Flames were supposedly destroyed on all planets after the Vennox regime crashed. If a quantity of the rock were in existence, and it fell into the wrong hands, there'd be trouble. "Of course, I regarded Karn's story as a wild dream, but it made corking good story material. I wrote it into a novel, and a week after it was completed, the manuscript was stolen from my study back on Earth." and laughed heartily. "The same old Flowers," I said. "Tell me, who's "And you can lay it all to the Green Flames. It seems incredible that a single shipload of the ore could effect such a wide ranged area, but in my opinion someone has found a means of making that quantity a thousand times more potent and is transmiting it en masse ." A heat ray! , the tough little two headed pack animal of the Venus hinterland. Any form of plane or rocket would have had its motor instantly destroyed, of course, by the magnetic force see, I'm positive the Green Flames have never been removed from the that broadcast would have meant little, a slight rebellion here, an it advance and retreat, saw two hyalescent eyes swim out of the murk. It charged, and with but a split second to act, I threw myself flat. There was a rush of mighty wings as the thing swept over me. Sharp talons raked my clothing. Again it came, and again I rolled swiftly, missing the thing by the narrowest of margins. The thing in the darkness turned like a cam on a rod and drove at us again. This time the old woman's heat gun clicked, and a tracery of purple flame shot outward. A horrible soul-chilling scream rent the air. A moment later something huge and heavy scrabbled across the ground and shot aloft. I stood frozen as the diminuendo of its wild cries echoed back to me. "In heaven's name, what was it?" "Hunter-bird," Grannie said calmly. "A form of avian life found here trained to pursue a quarry until it kills. It has a single unit brain and follows with a relentless purpose." "That it was sent by our enemy, the same enemy that shot at us in the the swamp had undergone a chemical change and evolved into a cohesive hand into one of those yellow streaks, he would have been devoured in a matter of seconds. type of visi set in one corner showed that Karn was not isolated from object of our trip, the prospector became thoughtful. "Green Flames, eh?" he repeated slowly. "Well yes, I suppose I could cigarette. "You know where it is, don't you?" "Dangerous?" "Yes and no. Only man I ever heard of who escaped their country outside of myself was the explorer, Darthier, three years ago. I got away because I was alone, and they didn't notice me, and Darthier escaped because he made 'em laugh." that all of us had been exposed to the insidious radiations. It was Karn who first sighted the ship. Striding in the lead, he suddenly halted at the top of a hill and leveled his arm before him. There it lay, a huge cigar-shaped vessel of blackened "What's that thing on top?" Karn demanded, puzzled. "Somebody's gone to a lot of trouble here," Ezra Karn observed. Grannie nodded. "Some kind of a broadcasting unit. The Green Flames in tholpane plate and their radiations stepped up by an electro-phosicalic process." Karn raised the butt of his pistol and brought it crashing against the Green Flames are more accessible." vessel's hull were tiers of rectangular ingots of green iridescent ore.

<question>:
Why was the Green Flame so sought after?

<options>:
A It was capable of shooting rays that would destroy every existance.
B It was used in warfare and needed to be protected
C It was too dangerous to be left unattended
D It was more powerful than any known drug

<answer>:

D