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

<passage>:
could not survive on the Earth, because the something else—capacities undeveloped by our science—after us the end Dark was the Ryzga mountain and forbidding among the cliffs and snow-slopes of the surrounding ranges: an immense and repellently geometric cone, black, its sides blood-tinted by the dying sun. Neena shivered, even though the surrounding cold could not reach her. warming cloak, a cloak that glowed softly golden in the deepening twilight, even as her love was about him. there was nothing. Perhaps the old man was resting. From the other She was beautiful and defiant, facing the red sunset and the black For the flame that had sprung between them at the Truce of New Grass, It was black night, as it would really be when Groz and his henchmen strange lights dipped above it cost. They hoarded their strength, helping one another It was starry night already when they saw the light from the Watcher's cave. The light shone watery and dim from beneath the hoary back of the glacier, and as they came nearer they saw why: the cave entrance was sealed by a sheet of ice, a frozen waterfall that fell motionless from the rocks above. They heard no sound. in the light that poured from within. disappointing. They had expected something more—an ancient giant, a tower of wisdom and strength. The Watcher was four hundred years old beside him even Groz, who had always seemed so ancient, was like a boy. all the walls were sheathed in ice—warm to the touch, bound fast against melting by the Watcher's will. Light blazed in reflections from Hot food and drink were before them almost at once. The Watcher regarded them with compassion as their eyes brightened and some of the shadow of "A pity, indeed. I would like to help you—but, you understand, I am the The Watcher was broodingly silent "We know the stories," Var said brusquely. "In the hollow heart of their power in the old man's look, the power of four hundred years' wisdom. its heart for energy, poisoned its seas and its air with the fume of their works, wrung its peoples dry for their labor ... and in each of and evil as no other people has been, because they wanted the stars. "Because of them we must build with dreams instead of iron, and our only fire is that of the Sun, and even now, two thousand years later, the strange plastic substances, debris of artifacts still showing the marks of their shaping—the scattered wreckage of the things they made. And "From the memories that the old Watchers have left here, and from the man wove a dream around them, and the bright ice-cave faded from their Black starless night, a sky of rolling smoke above the greatest city that was ever built. Only the angry light of fires relieved the city's darkness—that, and the blue-white lightning flashes that silhouetted the naked skeletons of buildings and were followed by thunder and a shaking of the earth. Along lightless streets, half choked with rubble and with the dead, the Ryzgas' might had been forged, eyes that stared white and half hope of new life on a world gutted and smoldering from the fulfilment of lightning blazed, and the city howled and screamed and burned. lifted in sudden awe. From the center, over the citadel, an immense white globe soared upward, rising swiftly without sound. Then the whole city, the dark tumuli of its buildings and its leaping fires and tormented faces, and the black sky over it, seemed to twist he and she were real and here, such had been the force of the dream, a rule would come again. These raised a black mountain from the Earth's "I have told you the story you know, and have shown you a glimpse of the in ignorance. Our world is unwise and sometimes evil, full of arrogance, but the Watcher drowned under wave upon wave of unconquerable languor. The bright cave swam and dissolved had wakened him. Across the cave he faced a young man who watched him coolly with dark piercing eyes that were familiar though he did not know Where's the Watcher?" There was a liquid tinkling as the ice-curtain collapsed the fresh breeze of morning swept into the cave. The youth beckoned to them, and It rose black and forbidding in the dawn as it had by sunset. To right the morning sun, but the mountain of the Ryzgas drank in the light and Below their feet the slope fell away into an opaque sea of fog, filling a mile-wide gorge. There was a sound of turbulent water, of a river dashed from rock to rock in its struggle toward the plain, but the curling fog hid everything. will be deceived and follow her, and by the time they catch her it will these can be borne—that I-you might be saved from death—which is alone irreparable.... But to become dizzied by the rapid flood of detail. Var felt a twinge of unfamiliar emotion that needs no blessing and feels no curse. Go!" doorway. It was an opaque yet penetrable well of darkness, opening into from the feeble sunshine that straggled through the fog-bank. With an abrupt motion he hurled it. The sun-globe vanished, as if the darkness had passed through to light up the depths beyond. For within the mountain something snapped suddenly alert—something alive yet not living, seeing yet blind. They felt light-sensitive cells tingle in too far to discern the rage that must contort his features, but the Behind Groz the figures of his followers loomed up as striding shadows. for the two on the mountainside the world turned upside down, the Together they plunged into the curtain of darkness. potential that seemed to whisper The sun-globe floated behind them, casting light before them down the Between wall and wall a blinding spindle of flame sprang into being, pulsed briefly with radiant energy that pained the eyes, and went out. The immaterial globe of light danced on before them. energies were stirring for the first time in centuries. The power that outside should crumble to ruin around them. increased with every step, its vibrations became sound, and its sound Without warning, lights went on. Blinking in their glare, Var and Neena room that was likewise ablaze with light. Cautiously they crept forward Its roof was vaulted its circular walls were lined with panels studded light flicked on and off in changing patterns, registering the shifting of magnetic fields, the fury of electrons boiling in vacuum.... this place whose remotest like they had never seen in the simplicity of He was a man of middle height and stocky build, clad in a garment of changing colors, of fabric delicate as dream-stuff. In his right hand, conveyed a queer suggestion of weariness or weakness, as if he were yet manner and his mind radiated a consciousness of power, a pride and open. They had a terse, disconnected quality that was strange and unsettling, and in part they were couched in alien and unintelligible interlopers with the dispassionate gaze of a scientist examining a new, "Culture: late barbarism. Handwork of high quality—good. Physically progression of logical thought, came a wave of raw emotion, devastating in its force. It was a lustful image of a world once more obedient, yet it was lined by a deeply one spot upon it. seven feet tall, flapping black amorphous limbs and flashing red eyes There was an instantaneous glare like heat lightning, and the monster crumpled in on itself, twitched briefly and vanished. But in that moment a light of inspiration had flashed upon Var, and it monster into the Ryzga's way—a mere child's bogey out of a fairy tale—the Ryzga had not recognized it as such, but had taken it for a will be no new beginning for you in civilization could never rise again, because it was a fire that consumed its fuel. After us man

<question>:
What is special about light in this story?

<options>:
A It is traded like a commodity
B It is the only way the adventurers nowhere to go
C It can be manipulated by the people
D It is liquid-like in its composition

<answer>:

C