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

<passage>:
widely scattered planets. Obviously there was no contact throughout the ages before space travel— 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!" feel that attraction to her? "Try Emmer," he suggested tiredly. "He'll find you irresistible, and he's even more savage than I am." "It is impressive," admitted Taphetta. "But I find it mildly distasteful to consider mating with someone who does not belong to my "Is he?" She smiled enigmatically. "Maybe, in a biological sense. Too species." accidental, very nearly represent the biological spectrum of human advantage?—for the children she intended to have. Outside of that, nothing mattered, and for the sake of alloying the lower with the higher, she was as cruel to herself as she was to him. And yet he wanted her. "I do think I love you," she said. "And if love's enough, I may marry development. you in spite of everything. But you'll have to watch out whose children unbroken line of evolution that could be traced back a billion years." "You're thinking of Earth," said Halden. "Humans require a certain kind toward the highest goal they could conceive of? Climbing over—no, through —everybody they could coerce, seduce or marry—onward and of planet. It's reasonable to assume that, if men were set down on a hundred such worlds, they'd seem to fit in with native life-forms on a few of them. That's what happened on Earth when Man arrived, there was actually a manlike creature there. Naturally our early evolutionists "But there are other worlds in which humans who were there before the Stone Age aren't related to anything else there. We have to conclude this section of the Milky Way." "And so, to account for the unique race that can interbreed across "Can you think of a better explanation?" asked Kelburn. "Something had to distribute one species so widely and it's not the result of parallel evolution—not when a hundred human races are involved, and only the human race." "I can't think of a better explanation." Taphetta rearranged his ribbons. "Frankly, no one else is much interested in Man's theories It was easy to understand the attitude. Man was the most numerous though not always the most advanced—Ribboneers had a civilization as high as anything in the known section of the Milky Way, and there were 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. very useful. A clear statement of their position was essential in helping him make up his mind. "You've heard of the adjacency mating principle?" asked Sam Halden. "Vaguely. Most people have if they've been around men." "We've got new data and are able to interpret it better. The theory is 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 "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?" was the most advanced human type present, but while there were differences, biological and in the scale of intelligence, it wasn't as great as once was thought. Anyway, non-humans weren't trained in the fine distinctions that men made among themselves. And, higher or invisible or not, didn't improve her appearance any. How could he still "That's because you're unique," said Halden. "Outside of your own world, there's nothing like your species, except superficially, and an equal lack of grace. He seemed to have difficulty in taking his eyes off Meredith, though, since he was a notch or so above her in the 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. 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 humans hadn't developed as much as lower races and actually weren't prepared for the multitude of life-forms they'd meet in space. Firmon's reaction was quite typical. smarter?" "I'd say that, yes. It must be a fairly intelligent creature to be so hard to get rid of. But it can be lured into traps, if the bait's strong enough." "Who knows? Their mental processes were certainly far different from ours. They may have thought we'd be better off without it. We do know they were looking for a special kind of planet, like Earth, because they visited so many of that type, yet different from it because they never stayed. They were pretty special people themselves, big and long-lived, and maybe they couldn't survive on any planet they found. Perhaps they had ways of determining there wasn't the kind of planet advanced and when they learned that, they may have altered their germ plasm and left us, hoping that some of us would survive. Most of us And they had, no matter who or what they were, biologically late or early, in the depths of the bronze age or the threshold of atomic—because they were human. That was sometimes a frightening thing for non-humans, that the race stuck together. They weren't actually curiosity." "Cultural discoveries," rumbled Emmer. "How did our ancestors live? When a creature is greatly reduced in size, as we are, more than "There may be things we can learn from them in mechanics or physics, but wouldn't you say they were better biologists than anything else?" Halden nodded. "Agreed. They couldn't find a suitable planet. So, working directly with their germ plasm, they modified themselves and technical advancement that multiplied unceasingly. The race that could "The electronic puppets were a good imitation, but the animals don't have to identify them as their species. If they're smart enough, they'll know the value of a knife, no matter who uses it." "What if they're smarter? Suppose they know a knife can't be used by a advanced. "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 own world. She had something else in mind. "I don't think I will, though. We might have children." "Would it be wrong?" he asked. "I'm as intelligent as you. We wouldn't have subhuman monsters." "It would be a step up—for you." Under her calm, there was tension. them start lower than I am?" The conflict was not new nor confined to them. In one form or another, it governed personal relations between races that were united against 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." It was true no one asked a member of a higher race to enter a 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 lead me astray." "Why not make a play for Kelburn? If you're going to be scientific

<question>:
What is both a gift and curse of humanity?

<options>:
A They are intellectually superior, but unable to mate with other species (and therefore grow their population) due to galactic mating laws
B They are biologically superior, but their restrictive mating abilities prevent them from growing their population as fast as other species
C They have a tendency to unify against a potential threat, but are unaware of how they could overtake other species through strength in unification
D They have a tendency to fall in love easily, which is difficult to manage when they become attracted to 'higher-level'  species, who are off limits

<answer>:

C