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

<passage>:
"Now Fweep ain't the brightest creature in the Universe, so he can't understand why we're so gosh-fired eager to leave. And as long as he's got Four, he's happy. Why should he make himself unhappy? As a favor to Four, he'd let us leave—if we'd leave Four here with him, which we ain't gonna do. "That's the problem. All we got to do is figure out the answer. No use Four? He's the only one who understands this thing." "He's outside, playing in the meadow with Fweep," Reba said, her voice soft. "No, here they come now." of exercising adult judgment and because he had the youngest adult the second planet was unusually heavy for its size. Then Fred said, 'That looks like heavy metals', and you said, 'Maybe uranium—'" "That's enough, Four," Junior interrupted. "Never mind what I said." Those were the Peppergrass men, four generations of them, looking remarkably alike, although some vital element seemed to have dwindled until Four looked pale and thin-faced and wizened. "And, Four," Reba said automatically, "don't call your father 'Junior.' It sounds disrespectful." Reba was Four's mother and Junior's wife. On her own, she was a noticed about the boy. "But everybody calls Junior 'Junior,'" Four complained. "Besides, Fred is Junior's father and Junior calls him 'Fred.'" button on his pircuit. The last light went out. "You've got work to do, have you? Whose flivver do you think this is, anyhow?" "It belongs to all of us," Four said shrilly. "You gave us all a sixth share." "That's right, Four," Grampa muttered, "so I did. But whose money bought it?" who makes the other one turn out the last light is the winner." "That's simple," Four said without hesitation. "The winning strategy is to—" for it. No dad-blamed machine is gonna outthink Grampa!" He snorted indignantly. Four shrugged his narrow shoulders and wandered to the view screen. "Look!" he said suddenly. "This planet not only has flora—it has fauna." He rushed to the air lock. "Four!" Reba called out warningly. "It's all right, Reba," Four assured her. "The air is within one per cent of Earth-normal and the bio-analyzer can find no micro-organisms Fweep?" Joyce drew her chair farther back toward the wall, revulsion on her face. "Four! Get that nasty thing out of here!" "You mean Fweep?" Four asked in astonishment. "Fweep?" queried the raspberry lips. "Fweep?" "If it's Four's friend," Reba said firmly, "it can stay. If you don't like to be around it, Grammy, you can always go to your own room." Joyce stood up indignantly. "Well! And don't call me 'Grammy!' It makes slowly clears. I think I'll try him with a bigger particle." "That's the idea, Four. You'll be a Peppergrass yet. How about building me a pircuit?" "You get the other one figured out?" right strategy. Dividing the thirteen lights into three sections of four each—" "That's right," Four agreed. "I can make you a new one by cannibalizing the other pircuit, but I'll need a few extra parts." the bottle away. "What is that stuff you drink, Grampa?" Four asked. rowboat?" "Yep," Grampa said. "Too easy." Four thought a moment. "There's a modern variation with three missionaries and three cannibals. Same river, same rowboat and only one of the cannibals can row. If the cannibals outnumber the missionaries—" followed closely by Junior. They were sweat-stained and weary, scintillation counters dangling heavily from their belts. it's broken or there's something about the gravity around here that just won't polarize." "It's these '23 models," Grampa put in disgustedly. "They never were would take a good look at the TV repairman when we get back to Earth. If we get back to Earth," he amended. "You can't be Four's father. All over the Universe, gravity is the same, and if it's gravity, the polarizer will polarize it." we won't have to stop with one child. We can have all the babies we want." "You know the law: one child per couple," Joyce reminded her frigidly. "I could think of worse things," Reba said. "I like your spunk, Reb," Grampa muttered. "Speaking of children," Junior said, "where's Four?" "Here." Four came through the airlock and trudged across the room, carrying a curious contraption made of tripod legs supporting a small box from which dangled a plumb bob. Behind Four, like a round, "Fweep?" it queried hopefully. "Not now," said Four. "Where've you been?" Reba asked anxiously. "What've you been doing?" "I've been all over Fweepland," Four said wearily, "trying to locate its center of gravity." "That's impossible," said Junior. "Not for Fweep," Four replied. The land of the Fweep rotated once on its axis, and Grampa lowered the nippled bottle from his lips. He sighed. "I got it figured out, Four," he said, holding out the pircuit proudly. "A missionary takes over a non-rowing type cannibal, leaves him there, and then the rowing cannibal takes over the other cannibal and leaves him there and—" Four nodded. "And that 'skin' of his—whatever it is he uses for skin—is more efficient in stopping particle emissions than several "And blow him up? I don't think it's possible, but even if it were, it might be a trifle more than disastrous for us." Four giggled at the thought. Joyce glared at him furiously. "Four! Act your age! We've got to do something with him. It's preposterous that we should be detained here at the whim of a mere blob!" "Don't call me 'Grammy!' Well, what are we going to do, just sit around and wait for that thing to die?" "We'd have a long wait," Four observed. "Fweep is the only one of his "He's no more improbable than people," said Four. "He wants to be helpful," Four replied without hesitation, "and he's lonely. After all," he added wistfully, "he's never had any friends." "How do you know all these things?" Joyce asked from her doorway, "Some," Four admitted. "Have you asked it to let us go?" "Fwiend," it said. "Well, now," Grampa said maliciously, his eye on Joyce, "that's no problem. We can just leave Four here with Fweep." In a voice filled with sanctimonious concern, Joyce said, "That's quite a sacrifice to ask, but—" "Joyce!" Reba cried, horrified. "Grampa was joking, but you actually mean it. Four is only a baby and yet you'd let him—" "Never mind, Reba," Four said evenly. "It was just what I was going to suggest myself. It's the one really logical solution." it would only say that the logical answer is the one I sug—" "Mother!" Junior warned. "We decided not to talk about it any more. Four is strange enough without encouraging him to think like a martyr. It's out of the question. If that's the only way we can leave this planet, we'll stay here until Four has a beard as white as Grampa's!" because he doesn't like gravity that's polarized in a straight line, and he don't want Four to leave him.

<question>:
Who is most intelligent?

<options>:
A Junior
B Grampa
C Fred
D Four

<answer>:

D