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

<passage>:
STRANGE EXODUS splashing through waist-deep water and climbing onto comparatively dry knolls. To right and left of him was the sullen noise of the river in it the bare ledge-rock of a stripped hillside until he stepped into a small pot-hole and lurched forward, and his outflung hands sank into the slime that covered a surface faintly, horrifyingly resilient. He recoiled as if seared, and retreated, slithering in the muck. For moments his mind was full of dark formless panic then he took a firm quiescent until morning—sleeping, if such things slept. those first hours of night if it did not move until dawn, the level The moonlight's fading again was merciful as he climbed the sheer, slippery face of the foot but he could hear the wash and chuckle of asleep—this is a nightmare." Once, listening to that insidious voice, he slipped and for instants hung dizzily by his hands, and for some minutes after he had found a new foothold merely clung panting with pounding heart. Some time after he had found courage to resume the climb, he dragged himself, gasping and quivering, to comparative safety on the broad and it seemed that the colossal body moved, swelling and expanded under the noonday sun, creamy white above and black and oily below, and beneath the black cloud something that writhed and flowed sluggishly in a cyclopean death agony. by tragedy the voice that went with it was flat, unemotional, pedantic. "There are so many of them, and we've destroyed so few—and to kill those few took our mightiest weapons. Examination of the ones that have from star to star in search of food, guided by instinct to suns and worlds like ours. Descending on such a planet, they move across its surface systematically ingesting all edible material—all life not mobile enough to avoid their march. They are like caterpillars that overrun a planet and strip it of its leaves, before moving on to the depths to Sun-type stars. All of them had crept endlessly eastward around the Earth, gutting the continents and churning the sea bottoms, prospect of death that was most crushing, but the death blow to his human pride, the star-storming pride of mind and will—defeated by that an attack of dizziness had made him fall, then he realized that the surface beneath him had shifted. Unmistakably even in the misty shape, as the vast protoplasmic mass below crawled, flowed beneath its integument. In slow peristaltic motion the waves marched eastward, made him unable to descend. As he lay where he had fallen, he felt that weakness creeping over him, no longer held in check by the will that had kept him doggedly plodding forward. Again he lay half conscious, in a lethargy that unchecked must grow steadily deeper until death. Isolated thoughts floated through his head. It occurred to him that he was now ideally located to conduct the experiments necessary to prove his theory of how to destroy the Clawing and hewing in the hole he had made, he tore out heavy slabs of the monster's flesh. A ripple that did not belong to the crawling motion ran over the thing's surface round about. Westover laughed wildly with a sudden hour later was replete. Either the long fast, or involuntary revulsion, or perhaps merely the motion of the creature brought on nausea, but he fought it sternly back and succeeded in keeping his strange meal down. steady, ravenous march to the east. But there was no motion the great Presently, though, he felt a faint shuddering and lift beneath his feet, and heard far stifled mutterings and sighs. it was as though the cessation of the rock and sway had exorcised the lethargy that had lain had passed here, touched by the madness that takes hermits and men lost in deserts or oceans. And his was a stranger solitude than any of those. Now he listened strainingly to the portentous sounds of change in the generating gases within itself, preparing to leave the ravished Earth. That was the meaning of its gargantuan belly rumblings. And they meant further that he must finally leave it—now or never—or be borne aloft to die gasping in the stratosphere. He had been hearing them again as he awoke—the distant muffled voices whose words he could not make out, not the small close ones that sometimes in the hot middays had spoken clearly in his ear and even called his name. The latter had to be, as he had vaguely accepted them even then, illusions—but the others—with his new clarity he was flat on the rough surface, beat on it with bare fists and shouted: "Help! Here I am! Help!" He paused to listen with fierce intentness, and heard nothing but the faint eructations deep inside the monster. benevolent understanding. "You have been alone too long here. Come with me—I will take you to the Doctor." into utter blackness—Westover knew that both the Preacher and his own wild hope were real. "Down here. Into the belly of Leviathan," said the old man solemnly, and Westover nodded this time with alacrity. The crawling descent through the twisting, Stygian burrow had much that ought to belong to a journey into Hell.... More than that, no demonologist's imagination could have conceived without experiencing the sheer horror of the yielding beslimed walls that seemed every moment squeezing in to trap them unspeakably. The air was warm and rank with the familiar heavy sweetish odor of the monster's colorless blood.... Then, as he knew it must, a light glimmered ahead, the sinus widened, at a chamber carved in the veritable belly of Leviathan. The floor underfoot was firm, as was the wall his shaking fingers tested. The Preacher stood beside him, breathing hard and mopping his forehead. But he brushed aside the deferential offers of the others: "No—I will firm-walled as the room they left behind. They emerged into a larger cavern, that like the first was lit—only now did the miracle of it obtrude itself in his dazed mind—by fluorescent tubes, and filled with "It's working," the other answered without looking up from the the trays, rising and bursting, rising and bursting with a curiously fascinating monotony. The subtly tense attitudes of the two initiates told Westover better than words that there was something hugely through the mill." called for the most radical innovation in our way of life." "Very well put," approved Sutton. "Except that you make it sound easy. By the time I'd worked it out like that, things were already in It was when we were still trying to find a poison for the beasts that I hit on the catalyst that makes their blood give up its oxygen—that's "Then," Westover glanced appreciatively around, "it looks like the main hazard is claustrophobia." "Don't worry about a cave-in. We're surrounded by solid cystoid tissue. But," Sutton's voice took on a graver note, "there may be other psychological dangers. I don't think all our people—there are secretion—hormone, enzyme or the like—to kill when suddenly Earth, because it's on such worlds they prey. A tapeworm can cross the Sahara desert in the intestine of a camel—" His voice was drowned in a vast hissing roar. An irresistible pressure distorted the walls of the chamber and scythed its occupants from their feet. Sutton staggered drunkenly almost erect, fought his way across the tilting floor to make sure of his precious apparatus. He turned back toward the others, bracing himself and shouting something

<question>:
Does the tone of the passage shift at all, and if it does, how does it shift?

<options>:
A It starts out bleak and quickly becomes hopeful
B There's no tone shift, it's consistently bleak throughout
C Most of the story is bleak but there are a few final moments of hope
D There's no tone shift, most of the passage is filled with dark humor

<answer>:

C