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

<passage>:
SPACEMAN ON A SPREE BY MACK REYNOLDS Illustrated by Nodel What's more important—Man's conquest of space, or one spaceman's life? I They also had a banquet for him, complete with speeches by such bigwigs of the Department of Space Exploration as Academician Lofting Gubelin and Doctor Hans Girard-Perregaux. There was also somebody from the government who spoke, but he was one of those who were pseudo-elected and didn't know much about the field of space travel nor the significance of Seymour Pond's retirement. Si didn't bother to The fact of the matter was, Si knew that his retiring had set them back. They hadn't figured he had enough shares of Basic to see him through decently. Well, possibly he didn't, given their standards. But Space Pilot Seymour Pond didn't have their standards. He'd had plenty of time to think it over. It was better to retire on a limited crediting, on a confoundedly limited crediting, than to take the two or three more trips in hopes of attaining a higher standard. He'd had plenty of time to figure it out, there alone in space on the In his position, I am afraid I would do the same thing he has." "That's nonsense, Hans. Zoroaster! Either you or I would gladly take Pond's place were we capable of performing the duties for which he has been trained. There aren't two men on North America—there aren't two men in the world!—who better realize the urgency of continuing our delving into space." Gubelin snapped his fingers. "Like that, either of us would give our lives to prevent man from completely abandoning the road to his destiny." His friend said drily, "Either of us could have volunteered for pilot training forty years ago, Lofting. We didn't." into industry. Automation being what it is, only a fraction of the population is ever called up. But Pond was. His industrial aptitude dossier revealed him a possible candidate for space pilot, and it was you yourself who talked him into taking the training ... pointing out the more pragmatic advantages such as complete retirement after but six trips, added shares of Basic so that he could enjoy a more comfortable life than most and the fame that would accrue to him as one of the very few who still participate in travel to the planets. Very well. He was sold. Took his training, which, of course, required long years of drudgery to him. Then, performing his duties quite competently, he made his six trips. He is now legally eligible for retirement. He was always paid lip service to adventure, hardships and excitement, but in actuality his instincts, like those of any other animal, lead him to the least dangerous path. Today we've reached the point where no one need face danger—ever. There are few who don't take advantage of the fact. Including you and me, Lofting, and including Seymour Pond." His friend and colleague changed subjects abruptly, impatiently. "Let's leave this blistering jabber about Pond's motivation and get to the point. The man is the only trained space pilot in the world. It will take months, possibly more than a year, to bring another novitiate pilot to the point where he can safely be trusted to take our next explorer craft out. Appropriations for our expeditions have been increasingly hard to come by—even though in on Appropriations, will terminate the whole Department of Space been a chance in a hundred that he'd have the bad luck to have his name pulled. But when it had been, Si had celebrated. When he had been informed that his physical and mental qualifications were such that he was eligible for the most dangerous occupation in the Ultrawelfare State and had been pressured into taking training for space pilot, he had celebrated once again. Twenty-two others had taken the training with him, and only he and Rod Cameroon had passed the finals. On this occasion, he and Rod had celebrated together. It Each time Si returned from one of his own runs, he celebrated. A spree, He had taken his schooling much as had his contemporaries. There wasn't any particular reason for trying to excell. You didn't want to get the reputation for being a wise guy, or a cloddy either. Just one of the Thus, Si was vaguely aware, it had always been down through the Si was going to do it differently this time. Nothing but the best. Wine, women, song, food, entertainment. The works. But nothing but the best. To start off, he dressed with great care in the honorable retirement-rank suit he had so recently purchased. His space pin he the Ultrawelfare State hardly one person in a hundred actually ever performed anything of value to society. The efforts of most weren't shot, and Si took the involuntary breath from which only heroes could sub-shots. Finally, the dash threw a green light and Si opened the Si took his time. Not that he really needed it. It was by far the most swank suite he had ever seen. One wall was a window of whatever size The auto-elevator murmured politely, "Yes, sir, the Kudos Room." At the door to the famous rendezvous of the swankiest set, Si paused a moment and looked about. He'd never been in a place like this, either. dreamed about, out there in the great alone, seated in the confining conning tower of his space craft. He sipped at the drink, finding it up to his highest expectations, and then swiveled slightly on his stool to take a look at the others present. Out Cooler, please, Fredric." Then deliberately added, "I thought the Kudos Room was supposed to be exclusive." Si cleared his throat. "Hey," he said, "how about letting this one be Si, disconcerted by the sudden reversal, said, "Yeah ... sure." "I been called Si so long, I don't even know who somebody's talking to bored with the whole thing. But old Doc Gubelin, I used to work under him in the Space Exploration department, he was hot for it." " Academician Si was expansive. "Why, sure. In the Space Department we don't have as though avoiding his face. "I ... I suppose it was that speech Doctor Girard-Perregaux made. There you stood, so fine and straight in your space-pilot uniform, the veteran of six exploration runs to the planets...." "Well," Si said modestly, "two of my runs were only to the Moon." "... and he said all those things about man's conquest of space. And the dream of the stars which man has held so long. And then the fact that you were the last of the space pilots. The last man in the whole world trained to pilot a space craft. And here you were, retiring." Si grunted. "Yeah. That's all part of the Doc's scheme to get me to take on another three runs. They're afraid the whole department'll be it'd take maybe a year before you could even send him on a Moon hop. So old man Gubelin, and Girard-Perregaux too, they're both trying to pressure me into more trips. Otherwise they got a Space Exploration Department, with all the expense and all, but nobody to pilot their ships. It's kind of funny, in a way. You know what one of those Si said, "Look, how about another drink?" read all about it. Have always known the names of all the space pilots and everything about them, ever since I was a child. I suppose you'd say I have the dream that Doctor Girard-Perregaux spoke about." after my first run and I found out what space cafard was." She frowned. "I don't believe I know much about that." Sitting in the Kudos Room with the most beautiful girl to whom he had already. But at this stage of the game when the whole ship's crammed tight with this automatic scientific apparatus and all, there's precious little room in the conning tower and you're the only man

<question>:
Why did the Department hope that Si would continue for three more space missions?

<options>:
A He didn't complain about the explorations and enjoyed his time in space.
B His required compensation was lower than the other pilots.
C It would take too long to train a new pilot to complete the explorations.
D He was the best of the best in the space exploration team.

<answer>:

C