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

<passage>:
"Not at all. The questions are quite explicit." admittance to any office you need to visit tonight. Therefore, it is the seal. "You said that already, but you can have dinner with me. Just company." time to match the instrument's metal contact points. The line of men was not impressed. He vaguely wondered if the little drama of the "Don't I take my 201 file?" "Sure, they don't put in screens here. Wanted to, but the boss "Your service tapes," the next noncom said. "Where you going?" Or I'll do it for another two." "I can get you a sensatia-tape," whispered the boy when they had how long it would take him to shake his—sea legs, the psychologist process. He cursed the grudging attitude of the headquarters satellite personnel and felt the impotence of a spaceman who had long forgotten motivated by envy soothed him as he clumsily let himself into the lock. "You are retarding the progress of others. Please respond more quickly to your orders." that was all there was to the sterilizing process. "Your clothing and effects will be in the dressing room immediately beyond the locked door." commanded the same voice he had heard before. "Turn your arm until the pain, but it is necessary to treat the small injury you have been disregarding." respect for the robot-controlled equipment of bases had risen. When II, didn't they?" been down for any period as yet." "Oh, I've landed a few times, even walked around for a while...." "With the help of paraoxylnebutal," supplied the captain. "Well, sure." The captain laughed reassuringly. "No, don't put up your guard again. The worst is over. Short of Gravitational conditioning, there is "Quite natural. But it being your first time—in quite a number of ways, I might add—it will be necessary for you to undergo some conditioning." "Conditioning?" asked Craig. "Yes. You have spent eleven years in space. Your body is conditioned to "Yeah, I know. Once on Gerymeade...." "You were ill, couldn't keep your balance, felt dizzy. That is why all spacemen carry PON, paraoxylnebutal, with them. It helps suppress certain physiological reactions to an entirely new set of conditions. Channels of the ear, for example. They play an important part in our awareness of balance. They operate on a simple gravity principle. Without gravity they act up for a time, then gradually lose function. Returning to gravity is rather frightening at first." "It meant more than that. There were excellent psychological reasons the beginning. I'll turn you over to psychometry for the usual tests During the days that followed, the psychologist seemed to Craig to intolerable. But even if he could accept the psychologist's authority for the really knew very much about Terra. So what? I know it won't be as it "Yet you are so completely sure you will want to live out your life but you're not talking me out of going back. If the service needs men so badly, let them get somebody else. I've put in time." "Do you really think that's my reason?" will be given a very liberal supply of PON—which you will definitely need. Good luck. You'll need that too." On the eighth day, two attendants, who showed the effects of massive doses of PON to protect themselves from the centrifugal force, had to carry a man out of the tank. Many others asked to be removed, begged to be allowed to withdraw their resignations. when the best of 'em want out." "How ... how do they know when you ought ... to come out?" he asked "Blood pressure. They get you just before you go into shock." "Well, it's keyed to give them some kind of signal." desperately wanted something to distract his mind from the ghastly conditioning process. "Can't they ... drop it down continuously?" "They tried that a few times—once when I was aboard. You wouldn't like "How ... many times ... do they drop it?" "Four times during the day, three at night. Twenty days." the nightmarish bodily sensations once more. He felt the cot slowly "We better take him out." "He'll go into shock." "... never make it the twelfth." "We better yank him." Attendants coming for to take me home.... Then it was better. Oddly, he passed the twelfth day easily. By the centrifuge's motors had diminished to a low hum. Either that or they Most of the men had passed through the torments of gravitational conditioning. The huge headquarters base centrifuge aboard the man-made satellite had gradually caused their bodies to respond once more to a On the eighteenth day, automatic machinery freed them from their imprisoning cots. Clumsily and awkwardly at first, the men began to walk, to hold their heads and arms in proper attitudes. They laughed and joked about it and kidded those who were slow at adjusting. Then they again began taking paraoxylnebutal in preparation for the free-fall flight to Terra. Only one of the score of men in the centrifuge tank remained voluntarily in his cot. "What will they do, exile him?" "Not to Chociante, if that's what you mean. They just jerked his space looking away. "Pick something to talk about. What do you figure on doing when you get to Terra, for instance?" "Sure," said the old spaceman, watching a group of young crewmen engaged in an animated conversation. "It's a good job. There's a future to it." Why did he have to explain anything at all to the old space tramp? But the old spaceman turned, smiling wryly. "Don't get hot, kid. I System, matter of fact. Never saw much of anything close up. I stood it stiffened their hearts. When they got old, it just pulled them in. sends the blood rushing through your veins. It's like loving. You don't you strictly alone. Except that it sucks you dry, takes all the soup out of you, leaves you brittle and old—old as a dehydrated piece of stand this whirligig conditioning, you're through with space." You got to watch the ones that don't. Yeah, you got to watch the ones that don't. Especially the old ones. They'll dump him, won't they? After a tracer is sent through. But it won't do any good. refolded it and jammed it in place. Smaller rolls of underclothing were It was the signal for relief in the passengers' quarters many were Earth was a lot different then than it is now. They don't have to tell I tried to send her some units once in a while. Don't know if she ever but she may need it. And maybe you can tell her a little bit about what it means to be out there. Tell her it's open and free and when of course. Purely routine." "We can allow the gentlemen to continue now, can't we? It wasn't that we believed for a minute, you understand ... purely routine." "You goin' to move on, buddy, or you want to go back?" screened "Hard to say," the other passenger said. "You'll get used to this. They get it over with quick." understand why the man had bothered until he realized that the only very briefly between questions. "Yes, naturally." "Conditions?" seated uncomfortably in the silent room. There was a distracted quality "Yes." He turned to face Craig briefly before continuing. "You must attempted to catch her eye had she not immediately occupied herself much the same way we would an extraterrestrial." "Three complete tours of duty, I believe." The other turned to the secretary. "You'll see that he is assisted in filing his application, won't you? A provisional Code II. That will "Will he need a food and—clothing ration also?" asked the girl, made uncomfortable."

<question>:
Why is it important to watch the ones who don't become physically ill during the conditioning process?

<options>:
A They could be tapped as leaders for Freedomite missions
B It is a sign that they are deviant extraterrestrials
C Their bodies' familiarity with gravity naturally makes them suspicious
D Their bodies may naturally produce paraoxynebutal

<answer>:

C