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

<passage>:
Tommy said finally. Tommy swallowed hard. "And if it happens to be six Tommy and Pete looked at each other, and Tommy's hands Charlie gulping a cup of coffee with a very smug-looking Tommy Grdznth. The coffee pot was floating gently about six feet "Charlie!" Tommy howled. "We've been trying to get you above the desk. So were the Grdznth and Charlie. when Tommy Heinz got himself into a hole. Not that he didn't like Tommy. Tommy was a good PR-man, in a beady Grdznth eye! What Tommy needed right now was Tommy turned purple. "We've got five months," he said Charlie chuckled. "Five months, he says. We figured the it'll make much difference to us." Charlie sank slowly down to the desk. He wasn't laughing any more. "We're never going to see any Grdznth babies. It's going to be a little too cold for that. The energy factor," he mumbled. "Nobody thought of wrinkles of satiny green fur. He knew, of course, that the Grdznth were mammals—"docile, peace-loving mammals," Tommy's PR-blasts had declared emphatically—but with one hands helplessly. "Oh, it won't be bad at all. Spike here was telling me. Mean temperature in only 39 below zero, lots of curved teeth glittered sharply. In spite of himself Pete gripped good clean snow, thousands of nice jagged mountain peaks. the seat as the Grdznth breathed at him wetly through damp nostrils. "For them," whispered Tommy. A lovely place, really. Just a little too cold for Grdznth. They "Misgauged?" said Pete. thought Earth was much nicer." hung down below flat reptilian eyes, and a double row of long The Grdznth nodded sadly. "It's horrible of me, but I just can't help it. I The Grdznth looked at him reproachfully. "The Wives, of course. The climate is so much better, and they mustn't be disturbed, you know." Pete thought of Tommy, red-faced and frantic, beating off he was busy sticking out his tongue at the Grdznth. the Grdznth was beginning to fade out. "Try four miles down and a thousand miles southeast," said smiling so much. He was wondering just how high Tommy was On the newly finished seventeenth floor, he found Tommy Tommy had lost weight since Pete had last seen him. His The sarcasm didn't dent Tommy. He led Pete through the Tommy gave a violent start. "Senator! Oh, dear." He flipped "Selling movies, right?" said Tommy. "Exactly," said Tommy. "Considering some of the movies "Yes, I know. And the Grdznth are getting worse by the hour. They're coming through in battalions—a thousand a day! The more Grdznth come through, the more they act as though they own the place. Not nasty or anything—it's that infernal 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 around them, a little point they didn't bother to tell us about. Anybody who tries anything fancy gets thrown like a bolt of "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 Tommy spread his hands helplessly. "If we knew, you'd scientists working with Charlie Karns. Most of the parallels are analogous, and we happen to be analogous to the Grdznth, a point we've omitted from our PR-blasts. They have an eight-planet system around a hot sun, and it's going to get lots hotter Tommy shook his head helplessly. "They picked a very sensible the females were chosen largely according to how pregnant they were." Pete grinned. "Grdznth in utero. There's something poetic that climate, at least not until they've been there long enough to get their glands adjusted. Seems we have just the right climate here for gestating Grdznth, even better than at home. So they came begging for permission to stop here, on the way feet thoughtfully. "This is all very touching," he said, "but it just doesn't wash. If the Grdznth are so unpopular with the looked narrowly at Tommy. "To be very blunt, what's the "Plenty," said Tommy heavily. "That's the trouble, you 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 Tommy said, "They're trying to. He's been working for "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 Tommy sighed. "In a word—yes. So far we've gotten nowhere down on a chair and burying his face in his hands. "I've failed. Failed!" The Grdznth sitting on the stool looked regretfully from the "Professional pride," said Tommy. "He can take twenty "You have just lost your job," he said to Tommy, with an "Indeed," said Pete. "Tommy, how fast can you get a PR-blast "Plenty," Tommy gulped. at Tommy pityingly. "You've tried to make them lovable, but Tommy's jaw sagged. "Pregnant," he said. got several hundred thousand pregnant Grdznth just waiting for all the little Grdznth to arrive, and nobody's given them a Grdznth are lovable?" "They probably look like salamanders," said Pete. "But tell "It's genius," chortled Tommy. "Sheer genius." sudden, harsh, or crude—but slowly, in a radio comment here or a newspaper story there, the emphasis began to shift from Grdznth in general to Grdznth as mothers. A Rutgers professor found his TV discussion on "Motherhood as an Experience" suddenly shifted from 6:30 Monday evening to 10:30 Saturday was averted. It was only a page 4 item, but it was a beginning. Determined movements to expel the Grdznth faltered, trembled with indecision. The Grdznth were ugly, they frightened little children, they on a twenty-four-hour schedule. Tommy Heinz grew ?" Tommy asked plaintively on Tommy mopped his forehead with his shirtsleeve. "Okay. for tolerance levels. Got that? How soon can we have it?" Analysis shook his head. "We could only make a guess with "Fine," said Tommy. "Make a guess." Turning back to Pete, Tommy rubbed his hands eagerly. good, but it's starting to sell! With the tolerance levels to tell people begin seeing what the Grdznth are giving us, they'll welcome them with open arms." "Hmmm," said Pete. "Sure, sure," said Pete. "It sounds great. Just a little bit Tommy blinked at him. "Too great? Are you crazy?" the Grdznth girls to gestate. But what are we hearing from Charlie?" nothing except a whole lot of Grdznth and more coming through just as fast as they can. I'm beginning to wonder what the Grdznth are "Three days?" cried Tommy. "What's wrong? Is he dead?" "The Program," Tommy said. "How's it going?"

<question>:
What was Tommy talking about when he mentioned "tolerance levels?"

<options>:
A The precision of the technology that the Grzdnth used
B The public's tolerance of the Grzdnth's presence on Earth
C The level of null-gravity that humans could withstand
D The Grzdnth Wive's heat tolerance

<answer>:

B