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

<passage>:
The work wasn't hard, but there were some sacrifices. You had to give up hope and freedom—and being human! Extensive research did not uncover any evidence that she had thought crimes were committed by shriveled, rat-faced types, and not by young biological engineers who still affected crewcuts. "Five or one." "Take the five," Jumpy advised. "Learn basket-weaving in a nice air-conditioned rehab clinic. A year on a changeling deal will seem a lot longer, even if you're lucky enough to live through it." with his head bent and turned to face Jumpy. "Nope," Asa said softly. "I'm going into a conversion tank. I'm going to be a muck man, Jumpy. I'm going out to Jordan's Planet and hunt of so-called social reorientation. But if he could get out to Jordan's Planet, with his physiology adapted to the environment of that wretched world, he could study the eggs under conditions no laboratory could duplicate. He might even be able to cause trouble for Hazeltyne. His only problem would be staying alive for a year. An interview with a doctor from the Conversion Corps was required for all persons who elected changeling status. The law stated that potential changelings must be fully informed of the rights and hazards of altered shape before they signed a release. The requirement held whether or not the individual, like Asa, was already experienced. By the time humanity traveled to the stars, medical biology had made it possible to regenerate damaged or deficient organs of the body. Regeneration was limited only by advanced age. Sometime after a man's two hundredth year his body lost the ability to be coaxed into growing new cells. A fifth set of teeth was usually one's last. As long as senescence could be staved off, however, any man could have bulging biceps and a pencil waist, if he could pay for the treatment. Until the medical associations declared such treatments unethical there was even a short fad of deliberate deformities, with horns at the temples particularly popular. From regeneration it was a short step to specialized regrowth. The techniques were perfected to adapt humans to the dozen barely habitable worlds man had discovered. Even on Mars, the only planet outside Earth in the solar system where the human anatomy was remotely suitable, a man could work more efficiently with redesigned lungs and temperature controls than he could inside a pressure suit. On more bizarre planets a few light-years away the advantages of changeling bodies were greater. Unfortunately for planetary development companies, hardly anyone wanted to become a changeling. High pay lured few. So a law was passed permitting a convicted criminal to earn his freedom by putting in one year as a changeling for every five years he would otherwise have had to spend in rehabilitation. "What types of changelings do you have orders for right now, doctor?" Asa asked the man assigned to his case. It would look suspicious if he "Four," answered the doctor. with the arm structure modified into pseudo-wings or gliding. Then we need spiderinos for Von Neumann Two. If you want the nearest thing we your tolerance for carbon monoxide and make you a bigger and better gorilla than the natives. Last, of course, there's always a need for muck men on Jordan's Planet." The doctor shrugged, as if naturally no one could be expected to alternatives. "What's the pay range?" he asked. "Why such a difference? Everyone knows about muck men living in the changeling comfortable in his new environment?" better than chinchilla fur and we can have you jumping like a end of the year." He leaned forward to fill in the necessary form. Since it was cheaper to transport a normal human than to rig special environments in a spaceship, every planet operated its own conversion chambers. On the space freighter that carried him from Earth Asa decided it was his imagination. He might have been dead cargo for all he learned about space travel. Nevertheless his time was not wasted. He had as a companion, or cellmate, another convict who had elected conversion to muck man. More thousand dollars waiting for me. That'll buy a two-year-old egg that Hardly anyone faced with the beauty of a Slider's egg bothered to question its workings. For a few expectant moments there would be only random, fitful gleamings, and then there would be a wild coruscation of light, dancing from one filament to the next in a frenzy of brilliance. It took about four years for a Slider egg to die. Beauty, rarity and fading value made the eggs a luxury item like nothing the world had ever seen. If Asa had found a means of keeping them alive it would have made him wealthy at the expense of the Hazeltyne monopoly. "You know what I think?" Kershaw asked. "I think those flashes are swooping out of nowhere at you." "I've been meaning to ask you," Asa said. "How do you handle the Sliders?" tell the tale." II Asa Graybar kept his normal form on Jordan's Planet just long enough to learn the discomfort of double gravity. He was told he needed another physical examination and was taken right in to a doctor. His heart was pounding to keep his blood circulating on this massive world, but the doctor had apparently learned to make allowances. to lose consciousness. "This is it!" he thought in panic. He felt someone ease him back down onto a wheeled stretcher. Before to back out of becoming a changeling, that he was on his way to the conversion tank right now. Everyone had seen pictures of muck men. It was different having one so that his arms dangled to the ground. The arms were as thick around as an ordinary man's legs. The hands had become efficient scoops, with broad fingers webbed to the first joint and tipped with spade-like claws. The skin was still pinkish but had become scaly. Not a thread of hair showed anywhere on the body, not even on the head. It would have been more bearable if the head had not retained strong and muscle coordination was perfect. He found himself leaping as high as Kershaw's head. "That's the way," Kershaw said approvingly. "Now get this on and we'll in two leaps. Attached to a harness across his shoulders and chest were a gun and a long knife. Asa was put through a series of exercises to get him used to his distorted body, to teach him how to leap and how to dig. He was shown He leaped twenty feet into the air for a closer look. Gazing at him with repugnance, after witnessing the end of his session him. Dorr had tried to get rid of him once and was now in an excellent position to make the riddance permanent. the others. "She wants to see what kind of suckers are making her rich." he is," said one of the others. "Just hope he doesn't take over the operations." III not at all uncomfortable, and the dripping air caressed their skins much as on top of it. The egg was flashing with a mad radiance, like a thousand diamonds scintillation of an egg was an effect of its calls to a mother Slider "We've got an egg but a Slider wants it back." "Thanks," Kershaw said. "Muck men stick together. You'll make a good "Makes no difference," said Kershaw, pointing upward. "Here comes the pounds on Earth, close to six hundred here. Dorr stared at him with narrowed eyes. Suddenly he smiled in a way that approximately by the body of the dead Slider. Dorr could return for the this strange new body, and if the Sliders left him alone.... "They feed at night, you know. And they eat their own kind," she said. it would make. hardly believe it yet. "Oh, back on Earth I can make a helicopter do stunts. But I wasn't used to this gravity. I don't suppose you could make this machine stand up straight?" that problem was settled. "If it's any comfort, I know how to handle

<question>:
What seems to be the primary benefit of becoming a changeling?

<options>:
A Efficient labor and reduced prison sentences.
B Regeneration of bodily organs.
C Extended life expectancy.
D Developing superhuman powers.

<answer>:

A