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

<passage>:
DOUBLECROSS by JAMES Mac CREIGH Revolt was brewing on Venus, led by the descendant of the first Earthmen to land. Svan was the leader making the final plans—plotting them a bit too well. [Transcriber's Note: This etext was produced from Planet Stories Winter 1944. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] lock, staring out over the dank Venusian terrain at the native town. He "Everything shipshape, I take it!" he commented. Lowry lifted his eyebrows. "Oh? But after all, they're human beings, just like us—" "Not any more. Four or five generations ago they were. Lord, they don't even look human any more. Those white, flabby skins—I don't like them." "Acclimation," Lowry said scientifically. "They had to acclimate themselves to Venus's climate. They're friendly enough." The Exec shrugged again. He stared at the wooden shacks that were the outskirts of the native city, dimly visible through the ever-present Venusian mist. The native guard of honor, posted a hundred yards from the Earth-ship, stood stolidly at attention with their old-fashioned proton-rifles slung over their backs. A few natives were gazing "Of course," Lowry said suddenly, "there's a minority who are afraid of us. I was in town yesterday, and I talked with some of the natives. They think there will be hordes of immigrants from Earth, now that we know Venus is habitable. And there's some sort of a paltry underground group that is spreading the word that the immigrants will drive the native Venusians—the descendants of the first expedition, that is—right down into the mud. Well—" he laughed—"maybe they will. After all, the fittest survive. That's a basic law of—" The annunciator over the open lock clanged vigorously, and a metallic The younger of the two women sighed. She might have been beautiful, in spite of her dead-white skin, if there had been a scrap of hair on her head. "Svan, I'm afraid," she said. "Who are we to decide if this is a good thing? Our parents came from Earth. Perhaps there will be trouble at first, if colonists come, but we are of the same blood." Svan laughed harshly. " They not human any more. The officer said it." The other woman spoke unexpectedly. "The Council was right," she agreed. "Svan, what must we do?" object?" "Good," said Svan. "Then we must act. The Council has told us that we alone will decide our course of action. We have agreed that, if the Earth-ship returns, it means disaster for Venus. Therefore, it must not return." An old man shifted restlessly. "But they are strong, Svan," he Earth." "Never get back to Earth?" the old man gasped. "Has the Council authorized—murder?" Svan shrugged. "The Council did not know what we would face. The object?" dull. "What is your plan?" he asked. feet, held up a shiny metal globe. "One of us will plant this in the ship. It will be set by means of this dial—" he touched a spot on the surface of the globe with a pallid finger—"to do nothing for forty hours. Then—it will explode. Atomite." He grinned triumphantly, looking from face to face. The grin bowl." Silently the girl picked up an opaque glass bowl from the broad arm of her chair. It had held Venus-tobacco cigarettes there were a few car, to look at the Earth-ship. No one will suspect—the whole city has been to see it already. One will get out, at the best point we can find. It is almost dusk now. He can hide, surely, in the vegetation. The other five will start back. Something will go wrong with the car—perhaps it will run off the road, start to sink in the swamp. The guards will be called. There will be commotion—that is easy enough, after all of the ship. The bomb is magnetic. It will not be noticed in the his subconscious indecision magnified, became opposition. The six conspirators in Svan's old ground car moved slowly along the main street of the native town. Two Earth-ship sailors, unarmed except They all are , he thought. Not one of them understands what this means. They're afraid. driving. "Let's get this done with." illuminating the narrow road and the pale, distorted vegetation of the jungle that surrounded them. Svan noticed it was raining a little. The present shower would deepen and intensify until midnight, then fall off again, to halt before morning. But before then they would be done. that followed its thunderous crash, a man's voice bellowed: "Halt!" The girl, Ingra, gasped something indistinguishable, slammed on the brakes. A Venusian in the trappings of the State Guard advanced on them from the side of the road, proton-rifle held ready to fire again. there is danger for all of us, if they discover he is missing. And keep a watch for other guards." Venus has no moon, and no star can shine through its vast cloud layer. Ensign Lowry, staring anxiously out through the astro-dome in the bow of the Earth-ship, cursed the blackness. something happens to the delegation?" "Then we're in the soup," the Exec said philosophically. "I told you the natives were dangerous. Spy-rays! They've been prohibited for the last three hundred years." "It isn't all the natives," Lowry said. "Look how they've doubled the guard around us. The administration is co-operating every way they know how. You heard the delegation's report on the intercom. It's this not be drawn away. I am glad I can't trust these five any more. If they must be destroyed, it is good that their destruction will serve a purpose. , his mind echoed. He smiled. At least, they would feel no pain, never know what happened. With the amount of atomite in that bomb in the compartment, they would merely be obliterated in a ground-shaking crash. since he could not know which was the one who had received the marked slip, and feared to admit it, it was better they all should die. He advanced along the midnight road to where the ground rose and the jungle plants thinned out. Ahead, on an elevation, were the rain-dimmed lights of the Earth-ship, set down in the center of a clearing made by its own fierce rockets. Svan's mist-trained eyes spotted the circling figures of sentries, and knew that these would be the ship's own. "Amazing," the surgeon said dryly. "Well, they won't do any bombing it? What about it?"

<question>:
What is one way the story’s setting, Venus, affects the characters and and sets up the plot?

<options>:
A The story takes place on Mars, not Venus. Over the last four or five generations, Mars’ conditions have caused its human colony to mutate in order to better survive. This causes a racial rift between humans from Earth and humans from Mars, which sets the story’s plot by imposing tension between the two groups.
B Over the last four or five generations, Venus’s conditions have caused its human colony to mutate in order to better survive. Differences in appearance cause a racial rift between humans from Earth and humans from Venus, which sets the story’s plot by imposing tension between the two groups.
C Over the last fifteen generations, Venus’s conditions have caused its human colony to mutate in order to better survive. This causes a racial rift between humans from Earth and humans from Venus, which sets the story’s plot by showing Venusians in a bad light.
D Over the last two or three generations, Venus’s conditions have caused its human colony to mutate into swamp people. This causes a holocaust of humans from Venus, which sets the story’s plot by imposing tension between the two groups.

<answer>:

B