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

<passage>:
But there had been no need to wait for that distant day. Scant years after he had written those prophetic words the thing was happening. Man had played unwittingly into the hands of those other minds in the other dimension. Man had waged a war and war had bred a pestilence. And the whole vast cycle of events was but that other dimension ... or was it one supreme intelligence ... had deliberately sown the seeds of dissension. The reduction of the had been there was greyish nothingness. Like an automaton he turned again and paced to the hall door. Weakly Mr. Chambers moved back to his chair in the corner. "So here I am," he said, half aloud. So there he was. Embattled in the last corner of the world that was left to him. The street was gone. The rest of his house was gone. This room still retained its form. This room, he knew, would stay the longest. And when the rest of forgotten, but whatever it was had been considered sufficiently revolutionary to cost Mr. Chambers his post at the university. October wind was rustling the dead leaves when Mr. Chambers A silver moon shone over the chimney tops and a chill, impish soaked up his will to make them walls and prints and lamps. He looked out the window into a blank world. His neighbors' houses already were gone. They had not lived with them as he had lived with this room. Their interests had been divided, thinly spread craft and evil.... Mr. Chambers turned his eyes back into the room. The clock was ticking slowly, steadily. The greyness was stealing into the room. The table and radio were the first to go. They simply faded away snarling and growling, snapping at his heels. But Mr. Chambers "Oh, well," said Mr. Chambers, "I never did like that very well." The wind whipped the muted words away and Mr. Chambers grumbled autumn darkness as he walked along. For there was nothing ... absolutely nothing in the world ... that he would let upset him. That was a tenet he had laid down twenty years ago. caught some excited words: "It's happening everywhere.... What do you think it is.... The scientists can't explain...." There was one answer to all of that. He simply didn't know. Nothingness advanced upon him, ate its way across the room, no sign of recognition. That was the way it had been for many years, ever since the people had become convinced that he did not The clock hadn't stopped. It wasn't there. Shaken, muttering to himself, Mr. Chambers let himself in his But silence was no strange thing to Mr. Chambers. Once he had symphonic broadcast had been interrupted to give a news flash. He had stopped reading newspapers and magazines too, had exiled himself to a few city blocks. And as the years flowed by, that self exile had become a prison, an intangible, impassable wall And so he knew that this was the year 1960 and that the wars in Europe and Asia had flamed to an end to be followed by a terrible plague, a plague that even now was sweeping through country after country like wild fire, decimating populations. A plague of proportion, of perspective? No, he hadn't. Take this room, for example. After twenty years it had come to be as much a part of him as the clothes he wore. Every detail of the room was engraved in his mind with ... showed an old sailing ship in the foreground on a placid sea. Far in the distance, almost on the horizon line, was the vague outline of a larger vessel. Further reverie became an effort as Mr. Chambers felt himself flee he stayed in the one place. His legs worked frantically, pumping like pistons, but he could make no progress. It was as if Mr. Chambers shivered, reached to turn up the collar of his coat, somewhere else. The cold of fear and horror, the chill of a half whispered thought. A deathly silence had fallen, a silence still measured by the pendulum clock. And yet a silence that held a different tenor than the happenings in the world from which he had excluded himself. He brought them back to mind now and lingered over the one Hints of a Europe and Asia swept almost clean of human life, of Gulping in fright, Mr. Chambers slammed the door shut, locked it by piece. He awoke, body drenched with perspiration. Vague light of early dawn filtered through the window. The clock on the bedside table showed 7:30. For a long time he lay there motionless. them, lost the keen edge of fantastic terror that lurked around them. The light through the windows slowly grew brighter. Mr. Chambers There was nothing outside the window. No shadows. As if there might be a fog. But no fog, however, thick, could hide the apple shriveled leaves reluctant to leave the parent branch. The tree was there now. But it hadn't been when he first had later he arose and almost ran across the room to the old mahogany thumbing slowly through the pages. For a moment the memory of happier days swept over him. lie in juxtaposition with ours. Perhaps we shall come upon a day, far distant, when our plane, our world will dissolve beneath our feet and before our eyes as A tumultuous idea hammered at him. Men had died by the millions all over the world. Where there had been thousands of minds there now were one or two. A feeble force to hold the form of matter intact. The plague had swept Europe and Asia almost clean of life, had blighted Africa, had reached South America ... might even have come to the United States. He remembered the whispers he had buildings disappearing. Something scientists could not explain. But those were merely scraps of information. He did not know the it all gripped him with damning clarity. There were not sufficient minds in existence to retain the material world in its mundane form. Some other power from another dimension was fighting to supersede man's control Abruptly Mr. Chambers closed the book, shoved it back in the case there wasn't any sun ... only an all pervading grayness that shrouded everything ... not a gray fog, but a gray emptiness that seemed devoid of life, of any movement. pictures without perspective, like twisted cardboard soldiers lining up for review on a misty morning. Once he stopped and looked back and saw that the grayness had closed in behind him. The houses were wiped out, the sidewalk faded into nothing. He shouted, hoping to attract attention. But his voice frightened him. It seemed to ricochet up and into the higher levels of the back over his shoulder and a queer feeling of inner numbness seemed to well over him. At that moment the gray nothingness appeared to thin ... the enveloping curtain fell away, and he saw.... Vague and indistinct, yet cast in stereoscopic outline, a vanishing point. Great shafts of multicolored light probed huge streamers and ellipses above the higher levels. And beyond, like a final backdrop, rose a titanic wall. It was that Mr. Chambers felt the eyes peering at him. down with malevolent composure. Then the city and the face slid out of focus the vision faded like a darkened magic-lantern, and the grayness moved in again. Mr. Chambers pushed open the door of his house. But he did not wood. The flames leaped merrily, dancing in the chimney's throat. Without removing his hat and coat, he sank exhausted in his favorite chair, closed his eyes then opened them again. world, his own private world, and as such it would be the last to go. But how long could he ... his brain ... maintain its existence? They couldn't take this away. The rest of the world might dissolve because there was insufficient power of thought to retain its outward form. Wheeling, he stared across the room. Was it his imagination, or Could it be that he was going mad? He had heard whispers when he had passed, whispers the gossiping housewives had not intended Perhaps we shall come upon a day, far distant, when our plane, our world will dissolve beneath our feet and before our eyes as

<question>:
Why was Mr. Chambers unable to see the apple tree by his window?

<options>:
A The apple tree had be chopped down
B There was a thick layer of fog outside
C His eyesight was failing him
D The current reality was starting to fade

<answer>:

D