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

<passage>:
above the desk. So were the Grdznth and Charlie. for hours! The operator—" "I know, I know." Charlie waved a hand disjointedly. "I told her to go away. I told the rest of the crew to go away, too." Charlie tipped an imaginary hat toward the Grdznth. "Spike tried to bury himself in his mother's coat collar. An indignant that. The energy factor," he mumbled. "Nobody thought of that except in passing. Should have, though, long ago. Two "You don't mind?" said the creature. they knew from the start that the differential was all on their side—a million of them unbalances four billion of us. All they needed to overload us completely was time for enough crossings." Grdznth were mammals—"docile, peace-loving mammals," A lovely place, really. Just a little too cold for Grdznth. They the seat as the Grdznth breathed at him wetly through damp The Grdznth nodded sadly. "It's horrible of me, but I just The Grdznth looked at him reproachfully. "The Wives, of "Oh, not many, not many at all. Only the Wives—half a million or so—and their spouses, of course." The creature clicked his talons nervously. "We haven't much more time, you know. Only a few more weeks, a few months at the most. If we couldn't have stopped over here, I just don't know what The passengers within earshot stiffened, glaring at Pete. The fat lady was whispering indignantly to her seat companion. sticking out his tongue at the Grdznth. "Oh, I don't mean to rush. It's been lovely, but—" Already the Grdznth was beginning to fade out. rumble rose around him like a wave. He was a Public Relations man to the core—but right now he was off duty. He chuckled to himself, and the passengers avoided him like the could almost smell the desperate tension of the place. He fought his way past scurrying clerks and preoccupied poll-takers "Me?" said Pete. "I'd never let down a pal." giz." He turned back to Pete with a frantic light in his eye. "Good old Pete. Just in time. Just. Eleventh-hour reprieve. Have a "Yes, I know. And the Grdznth are getting worse by the The more Grdznth come through, the more they act as though politeness that people hate most, I think. Can't get them mad, can't get them into a fight, but they do anything they please, and go anywhere they please, and if the people don't like it, the Grdznth just go right ahead anyway." the Grdznth a bit—they have personal protective force fields "I wish I knew. I mean, for sure. The psych-docs say no. The Grdznth agreed to leave at a specified time, and something in their cultural background makes them stick strictly to their agreements. But that's just what the psych-docs think, and they've been known to be wrong." "And the appointed time?" are analogous, and we happen to be analogous to the Grdznth, here for gestating Grdznth, even better than at home. So they came begging for permission to stop here, on the way through, to rest and parturiate." it just doesn't wash. If the Grdznth are so unpopular with the Pete, with Tommy beaming over his shoulder. "The Grdznth can cross through. They've been able to do it for a long time. According to our figuring, this must involve complete control of mass, space and dimension, all three. And time comes into one of the three—we aren't sure which." closed the box with a click. "This is one of their children's toys, and theoretically, it can't work. Among other things, it takes concept of time travel that makes some kind of sense. And power! If there's an energy differential of any magnitude—" He shook his head sadly. "We'll also know the time-differential," said Tommy hopefully, "and how long the Grdznth gestation period will be." "It's a fair exchange," said Charlie. "We keep them until the girls have their babies. They teach us the ABC's of space, with them for another six months or so." Tommy sighed. "In a word—yes. So far we've gotten nowhere at a thousand miles an hour." "I can't do it!" the cosmetician wailed, hurling himself The Grdznth sitting on the stool looked regretfully from the "How about the 'jolly company' approach?" "Tried it. There's nothing jolly about them. They pop out of nowhere, anywhere. In church, in bedrooms, in rush-hour jammed autos like General Sherman tanks. "Ulcers," said Tommy. "City traffic isn't enough of a mess as it is. And they don't do anything about it. They apologize profusely, but they keep coming through." The two started on for the office. "Things are getting to the breaking point. The people are wearing thin from sheer annoyance—to say nothing of the nightmares the kids are having, and the trouble with women fainting." can manage to do clear. If the Grdznth do not go, I go." "We can have prelims six hours after the PR-blast. Pete, if you have an idea, tell us!" for all the little Grdznth to arrive, and nobody's given them a Grdznth are lovable?" Grdznth in general to Grdznth as mothers. A Rutgers professor Determined movements to expel the Grdznth faltered, trembled with indecision. The Grdznth were ugly, they frightened little children, they were a trifle overbearing in their insufferable stubborn politeness—but in a civilized world you just couldn't turn expectant mothers out in the rain. Not even expectant Grdznth mothers. stomach pains. "Why don't people respond the morning the third week started. "Haven't they got any feelings? The blast is washing over them like a wave and there in his eye. "How soon?" "You want yesterday's rushes?" "What do you think I want? Any sign of a lag?" Now listen: we need a special run on all response data we have for tolerance levels. Got that? How soon can we have it?" the data so far." "Fine," said Tommy. "Make a guess." "Give us three hours," said Analysis. "You've got thirty minutes. Get going." Turning back to Pete, Tommy rubbed his hands eagerly. us how long we can expect this program to quiet things down, we can give Charlie a deadline to crack his differential factor, or it's the ax for Charlie." He chuckled to himself, and paced an afternoon on the beach, and back in time for supper. A hundred miles to the gallon for the Sunday driver. When people begin seeing what the Grdznth are giving us, they'll welcome them with open arms." "Well, why won't they? The people just didn't trust us, that we're standing in this thing? We're out on a limb—way out. We're fighting for time—time for Charlie and his gang to crack the puzzle, time for the Grdznth girls to gestate. But what are we hearing from through just as fast as they can. I'm beginning to wonder what the Grdznth are giving us." "Well, they can't gestate forever." "Maybe not, but I still have a burning desire to talk to Charlie. Something tells me they're going to be gestating a little too long." They put through the call, but Charlie wasn't answering. "Sorry," the operator said. "Nobody's gotten through there for three days." minutes." "Get him on the wire," Tommy said. "That's orders." There was dead silence in the room. "Baby Grdznth,"

<question>:
Why were the Grdznth so polite?

<options>:
A They don't want to upset anyone
B They were afraid of humans
C It is part of their culture
D They need time to pass without causing trouble

<answer>:

D