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

<passage>:
found out." She took his arm as they gazed past the electrified fence at the Earth below and to the west. "It's impressive, isn't it?" she said. "I wonder if that's Indiana way over there?" mean, how do we know Superior is maintaining the same position up here as it used to down there?" "We could tell by the sun, silly." "Of course," he said, grinning at his stupidity. "And I guess we're not high enough to see very far. If we were we'd be able to see the Great cloudbank and, a second later, veered sharply. They could make out UAL on the underside of a wing. As it turned they imagined they could see Don Cort, stranded on that rising town, was beginning to suspect that accepted their rise in the world as being due to one of their local townspeople, a crackpot professor. But after a couple of weeks of floating around, it began to be obvious clean clothes, you're not going to like me." "You're still quite acceptable, if a bit whiskery." She stopped, still Superior had been. Knaubloch couldn't see the extent of the pit because it was too dark, it reported that it looked as if a great ice-cream scoop had bitten into the Ohio countryside. shortly after midnight. Someone pointed out that October 31 was Halloween and that midnight was the witching hour. when he came out the other side he reported that the pit was concave, relatively smooth, and did not smell of high explosives. He'd found no people, no houses—no sign of anything except the pit itself. hoping this was Columbus, where he planned to catch a plane east. But it wasn't Columbus. All he could see were some lanterns jogging as trainmen hurried along the tracks. The conductor looked into the car. The redhead across the aisle in whom Don had taken a passing interest earlier in the evening asked, "Why did "Somebody flagged us down," the conductor said. "We don't make a station stop at Superior on this run." The girl's hair was a subtle red, but false. When Don had entered the club car he'd seen her hatless head from above and noticed that the hair along the part was dark. Her eyes had been on a book and Don had the opportunity for a brief study of her face. The cheeks were full and untouched by make-up. There were lines at the corners of her mouth which indicated a tendency to arrange her expression into one of disapproval. The lips were full, like the cheeks, but it was obvious that the scarlet lipstick had contrived a mouth a trifle bigger than the one nature had given her. Her glance upward at that moment interrupted his examination, which had been about to go on to her figure. Later, though, he was able to observe that it was more than adequate. If the girl had given Don Cort more than that one glance, or if it had been a trained, all-encompassing glance, she would have seen a man in his mid-twenties—about her age—lean, tall and straight-shouldered, with once-blond hair now verging on dark brown, a face neither handsome nor ugly, and a habit of drawing the inside of his left cheek between his teeth and nibbling at it thoughtfully. But it was likely that all she noticed then was the brief case he reason why his interest in the redhead had been only passing. Don hesitated, shrugged at the redhead, said, "Excuse me," and followed Some sort of barricade had been put up across the tracks and it was covered with every imaginable kind of warning device. There were red swelled with pride, it seemed, as he made a theatrical gesture. "Behold," he said. "Something even Columbus couldn't find. The edge of the world." True, everything seemed to stop, and they could see stars shining low on the horizon where stars could not properly be expected to be seen. Standing on tiptoe and repressing a touch of giddiness, Don looked over Don Cort, sitting in the back seat of the car with the redhead from the "No. There wasn't any sensation at all, as far as I noticed. I was watching the late show—or trying to. My house is down in a hollow and reception isn't very good, especially with old English movies. Well, all of a sudden the picture sharpened up and I could see just as plain. Then was frowning. "Are you thinking," he asked, "that Mayor Civek was perhaps just a little less than completely honest with us?" "I'm thinking," she said, "that I should have stayed with Aunt Hattie around a corner, gesticulating wildly to someone wearing a white laboratory smock. and things were going on. He had a view of the campus from his window. A bright sun shone on young people moving generally toward a squat building, and other people going in random directions. The first were students going to breakfast, he supposed, and the others were faculty members. The air was very clear and the long morning shadows distinct. others had gone from their unmade beds. He shivered as he stepped outdoors. It was crisp, if not freezing, and his breath came out visibly. First he'd eat, he decided, so he'd be strong enough to go take a good look over the edge, in broad daylight, to the Earth below. knew, but as he was looking for a table a willowy blonde girl smiled and gestured to the empty place opposite her. "I'll find a way. I'm more interested at the moment in how I got up here." Don blinked at the headline: being a natural-born needler, and Father has disowned me intellectually ever since." "How old are you, Miss Garet, if I may ask?" She sat up straight and tucked her sweater tightly into her skirt, emphasizing her good figure. To a male friend Don would have described the figure as outstanding. She had mocking eyes, a pert nose and a mouth of such moist red softness that it seemed perpetually waiting to be "On such short notice?" Don was intrigued. Last night the redhead from the club car had repelled an advance that hadn't been made, and this morning a blonde was apparently making an advance that hadn't been They found it coursing along between the banks. "Looks just about the same," she said. "That's funny. Come on The brink, as Alis called it, looked even more awesome by daylight. Everything stopped short. There were the remnants of a cornfield, with the withered stalks cut down, then there was nothing. There was South Creek surging along, then nothing. In the distance a clump of trees, with a few autumn leaves still clinging to their branches, simply ended. "Where is the water going?" Don asked. "I can't make it out." "Down, I'd say. Rain for the Earth-people." "I should think it'd be all dried up by now. I'm going to have a look." "Don't! You'll fall off!" "I'll be careful." He walked cautiously toward the edge. Alis followed panting, head pressed to the ground. "How do you feel?" Alis asked. "Scared. When I get my courage back I'll pick up my head and look." ankle and held it tight. "Just in case a high wind comes along," she said. "Thanks. It helps. Okay, here we go." He lifted his head. "Damn." "I can't see too well, but that's my impression. Hold on now. I'm coming back." He inched away from the edge, then got up and brushed himself out of play, Don thought) and on to the edge again. But as they approached what they were forced to consider the source of the creek, they found a wire fence at the spot. "This is new," Alis said. The fence, which had a sign on it, warning—electrified , was the tarp and fence. "Look how it comes in spurts," Alis said.

<question>:
What had given it away to Don that the attractive redhead he saw on the train was not actually a natural redhead?

<options>:
A Her skin tone was too off to match the hair color.
B The red tone of her hair was far too bright to be considered natural.
C She was carrying box hair dye.
D Her dark roots were showing.

<answer>:

D