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 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 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 dimension—but the energy differential was the important one." the cabin. "Sit down," Pete said to the creature. "Relax. Cheerful reception these days, eh?" "You don't mind?" said the creature. 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 of them sitting about a foot away Pete had to fight down a A lovely place, really. Just a little too cold for Grdznth. They thought Earth was much nicer." "For them," whispered Tommy. the seat as the Grdznth breathed at him wetly through damp nostrils. "Misgauged?" said Pete. The Grdznth nodded sadly. "It's horrible of me, but I just can't help it. I always "For them," Charlie said. Transcriber's Note: airplane," said Pete. "Why Florida?" The Grdznth looked at him reproachfully. "The Wives, of course. The climate is so much better, and they mustn't be disturbed, you know." "Of course," said Pete. "In their condition. I'd forgotten." Tommy had lost weight since Pete had last seen him. His then added, "See if you can get Charlie down here with his giz." "Selling movies, right?" said Tommy. "To people who don't want to buy them, right?" "Exactly," said Tommy. "Considering some of the movies The more Grdznth come through, the more they act as though they own the place. Not nasty or anything—it's that infernal 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. Pete nodded slowly. "Are they?" "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 minus a month for the time differential. That's strictly tentative, according to the math boys. It's a parallel universe, one of several thousand already explored, according to the Grdznth 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 through parallel after parallel trying to find one they can migrate to. They found one, sort of a desperation choice. It's Tommy shook his head helplessly. "They picked a very sensible system for getting a good strong Grdznth population on the new parallel as fast as possible. The males were picked for brains, education, ability and adaptability the females were chosen largely according to how pregnant they were." Pete grinned. "Grdznth in utero. There's something poetic about it." "Just one hitch," said Tommy. "The girls can't gestate in 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 through, to rest and parturiate." "So Earth becomes a glorified incubator." Pete got to his feet thoughtfully. "This is all very touching," he said, "but it just doesn't wash. If the Grdznth are so unpopular with the masses, why did we let them in here in the first place?" He looked narrowly at Tommy. "To be very blunt, what's the parking fee?" "Plenty," said Tommy heavily. "That's the trouble, you see. The fee is so high, Earth just can't afford to lose it. Charlie Karns'll tell you why." box. "It's the parallel universe business, of course," he said to 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 the differential." "And if you do, then what?" Charlie took a deep breath. "We'll have inter-dimensional control, a practical, utilizable transmatter. We'll have null-gravity, which means the greatest advance in power utilization 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, mass and dimension." Pete nodded. "That is, if you can make the people put up Tommy sighed. "In a word—yes. So far we've gotten nowhere "Professional pride," said Tommy. "He can take twenty "Ulcers," said Tommy. "City traffic isn't enough of a mess "You have just lost your job," he said to Tommy, with an clear. If the Grdznth do not go, I go." "That would never do, of course," murmured Pete. "An assistant on the job," Tommy said quickly. "A very "Plenty," Tommy gulped. 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 side glance." He turned to Tommy. "Get some copywriters down here. Get a Grdznth obstetrician or two. We're going to Grdznth are lovable?" "They probably look like salamanders," said Pete. "But tell the people anything you want. If we're going to get across the "It's genius," chortled Tommy. "Sheer genius." 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 ?" Tommy asked plaintively on 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." "Hmmm," said Pete. "Sure, sure," said Pete. "It sounds great. Just a little bit Tommy blinked at him. "Too great? Are you crazy?" for Charlie and his gang to crack the puzzle, time for the Grdznth girls to gestate. But what are we hearing from Charlie?" "Pete, Charlie can't just—" "That's right," said Pete. " 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 giving us."

<question>:
What was Tommy referring to when he said that the "parking fee" was "plenty?"

<options>:
A The Grzdnth would give the humans immense amounts of money for letting them stay.
B The Grzdnth would charge the humans in order to stay on their planet
C The Grzdnth would let the humans live for letting them stay.
D The Grzdnth would give the humans the knowledge of inter-dimensional travel for letting them stay.

<answer>:

D