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

<passage>:
She provocatively arched her back. Not even the women of Kelburn's race had a body like hers and she knew it. "Racially, there should be a chance," she said. "Actually, Kelburn and I would be infertile." "Can you be sure?" he asked, knowing it was a poor attempt to act unconcerned. race an inferiority complex—but then he tried to climb it! In repose, Taphetta the Ribboneer resembled a fancy giant bow on a package. His four flat legs looped out and in, the ends tucked under his wide, thin body, which constituted the knot at the middle. His neck Taphetta rattled the head fronds together in a surprisingly good imitation of speech. "Yes, I've heard the legend." "It's more than a legend," said Sam Halden, biologist. The reaction was and yet each planetary race can interbreed with a minimum of ten others ! That's more than a legend—one hell of a lot more!" "It is impressive," admitted Taphetta. "But I find it mildly distasteful to consider mating with someone who does not belong to my species." "That's because you're unique," said Halden. "Outside of your own that's true of all other creatures, intelligent or not, with the sole a corresponding span of fertility. Emmer just misses being able to breed with my kind, but there's a fair chance that I'd be fertile with Meredith and a similar though lesser chance that her fertility may extend to Kelburn." Taphetta rustled his speech ribbons quizzically. "But I thought it was proved that some humans did originate on one planet, that there was an unbroken line of evolution that could be traced back a billion years." commented Taphetta dryly. "It seems an unnecessary simplification." "Can you think of a better explanation?" asked Kelburn. "Something had to distribute one species so widely and it's not the only the human race." "I can't think of a better explanation." Taphetta rearranged his others—and humans were more than a little feared. If they ever got together—but they hadn't except in agreement as to their common origin. Still, Taphetta the Ribboneer was an experienced pilot and could be very useful. A clear statement of their position was essential in helping him make up his mind. "You've heard of the adjacency mating that humans who can mate with each other were once physically close. We've got a list of all our races arranged in sequence. If planetary race F can mate with race E back to A and forward to M, and race G is fertile only back to B, but forward to O, then we assume that whatever Taphetta rustled. "The math is accurate?" "As accurate as it can be with a million-plus body problem." "To the best of our knowledge," said Kelburn. "And whereas there are humans who are relatively near and not fertile, they can always mate with those they were adjacent to two hundred thousand years ago !" "The adjacency mating principle. I've never seen it demonstrated," murmured Taphetta, flexing his ribbons. "Is that the only era that satisfies the calculations?" Taphetta waved a ribbon at the chart. "And you think that where the two ability." Taphetta crinkled politely at the reference to his skill. "I had other plans, but I can't evade professional obligations, and an emergency such as this should cancel out any previous agreements. Still, what are profits from any discoveries we may make." "I'm complimented that you like our contract so well," said Taphetta, "but I really must have our own unsimplified version. If you want me, you'll take my contract. I came prepared." He extended a tightly bound mating scale, he shouldn't have been so interested. But his planet had been inexplicably slow in developing and he wasn't completely aware of his place in the human hierarchy. Muttering something about primitive women, Firmon turned to the "To everybody else, too, but the tapeworm hasn't got lungs. He breathes through a million tubes scattered over his body." It would do no good to explain that Taphetta wasn't a worm, that his evolution had taken a different course, but that he was in no sense less complex than Man. It was a paradox that some biologically higher Halden. "Do anything you can to give it to him." "Can't. This is as good as I can get it. Taphetta thought you could do something about it." Perhaps it was intended to discourage Firmon, but he wished she hadn't said it. It didn't help the situation at all. Taphetta sat in a chair designed for humans. With a less flexible body, he wouldn't have fitted. Maybe it wasn't sitting, but his flat legs were folded neatly around the arms and his head rested comfortably on tells me you're contemplating an experiment. I don't like it." The Ribboneer's distaste subsided. "What kind of creatures are they?" four-legged animal with two antennae at the lower base of its skull. A typical pest." Taphetta rustled. "Have you found out how it got on?" "It was probably brought in with the supplies," said the biologist. "Considering how far we've come, it may have been any one of a half so hard to get rid of. But it can be lured into traps, if the bait's strong enough." "That's what I don't like," said Taphetta, curling. "Let me think it "I don't question your authority," crinkled Taphetta. "To me, all humans—late or early and male or female—look remarkably alike. If you are an archeologist, that's enough for me." He paused and flicked his "A faster-than-light drive and an extremely long life," mused Taphetta. plasm and left us, hoping that some of us would survive. Most of us did." "This special planet sounds strange," murmured Taphetta. Taphetta. "We helped them," said Emmer. And they had, no matter who or what they were, biologically late aloof. The unknown ancestor again. Who else had such an origin and, it was tacitly assumed, such a destiny? Taphetta changed his questioning. "What do you expect to gain from this discovery of the unknown ancestor?" It was Halden who answered him. "There's the satisfaction of knowing "No doubt," said Taphetta. "An archeologist would be interested in "I thought so," said Taphetta. "I never paid much attention to your fractionally and ceaselessly. "I don't like to, but we'll have to risk using bait for your pest." terms don't permit you to withhold any discovery for the benefit of one race." Taphetta was wrong there had been no intention of withholding anything. Halden examined his own attitudes. He couldn't, and it was too late now—whatever knowledge they acquired would have to be shared. That was what Taphetta had been afraid of—there was one kind of technical advancement that multiplied unceasingly. The race that could improve itself through scientific control of its germ plasm had a start "It's almost a curse, isn't it?" She laughed and took the curse away by leaning provocatively against him. "But barbaric lovers are often nice." her, I'm merely a passionate savage. non-humans, but held sharp distinctions themselves. "I haven't asked you to marry me," he said bluntly. "Because you're afraid I'd refuse." permanent union. "Why did you ever have anything to do with me?" demanded Halden. "Love," she said gloomily. "Physical attraction. But I can't let it

<question>:
What is ironic about Taphetta's contempt for mating among species?

<options>:
A Taphetta can only survive if they mate with another species
B Taphetta is actually jealous about other species' ability to intermix
C Taphetta is likely a result of mating among species
D Taphetta is biologically unable to mate with other species

<answer>:

D