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

<passage>:
Brightside Crossing by Alan E. Nourse the patrons were few in number. Across to the right was a group that Baron knew vaguely—Andean climbers, or at least two of them were. Over near the door he recognized old Balmer, who had mapped the sky and hotter. Without our ultra-violet screens and glare he looked weary and immensely ugly. His cheeks and healing. The stranger said, “I’m glad you waited. I’ve heard you’re planning to attempt the Brightside.” Baron stared at the man for a moment. “I see you can read telecasts,” he said coldly. “The news was correct. We are going to make a Brightside Crossing.” “At perihelion?” “Of course. When else?” their Brightside Crossing. On the fifth driving period out, the terrain began to change. It looked the same, but every now and then it got to. You’re the only man on Earth who’s attempted a Brightside Crossing and lived through it! And the story you cleared for the news—it was nothing. We need details thick and tenacious, splattering around in steaming gobs as “It’s simple. We failed because it can’t be done. We couldn’t do it and neither can you. No human beings will ever cross the Brightside alive, not if they try for centuries.” “Nonsense,” Baron declared. “We will.” Claney shrugged. “I was there. I know what I’m saying. You broad flat plateau, dodging a network of gaping surface cracks—winding back and forth in an effort to keep the machines on solid rock. I couldn’t see far ahead, because of the yellow haze I’d been interested in the Brightside for almost as long as I can remember (Claney said). I guess I was about ten when Wyatt and Carpenter made the last attempt—that was in 2082, fifty yards to the left, then back to the right. There was only one place that looked like a possible crossing a long, narrow ledge of gray stuff that lay down across Twilight Lab up there and began to get Brightside into my “What trip?” “Brightside of Mercury,” the Major said. I whistled cautiously. “At aphelion?” He threw his head back. “Why try a Crossing at aphelion? heat, just to have some joker come along, use your data and drum you out of the glory by crossing at perihelion forty-four days later? No, thanks. I want the Brightside without any nonsense about it.” He leaned across me eagerly. “I want to make a Crossing at perihelion and I want to cross on the surface. If it. Nobody had, since Wyatt and Carpenter disappeared. Mercury turns on its axis in the same time that it wheels around the Sun, which means that the Brightside is always facing in. That makes the Brightside of Mercury at perihelion the hottest place in the Solar System, with one single exception: the surface of the Sun itself. would cross it. I wanted to be along. The Twilight Lab, near the northern pole of Mercury, was the Twilight Lab wasn’t particularly interested in the Brightside, of course—the Sun was Sanderson’s baby and he’d picked Mercury as the closest chunk of rock to the Sun that could hold his observatory. He’d chosen a good location, too. On Mercury, the Brightside temperature hits 770° F. at perihelion and the Darkside runs pretty constant at -410° F. No permanent installation with a human crew could survive at either extreme. But with Mercury’s wobble, the twilight zone between Brightside and Darkside offers something closer to survival temperatures. Sanderson built the Lab up near the pole, where the zone 60 degrees with the libration. The Solar ’scope could take that Poor Jack met us at the rocket landing almost bawling, Sanderson had given him such a gloomy picture of what Brightside “No. Are you worried?” “Not exactly. But Brightside is no place to count on luck.” The Major laughed. “I don’t think we need to worry about say much about it. Stone was getting edgy and so was I. We spent the second day studying charts of the Brightside, such as they were. The best available were pretty poor, taken from so surface activity.” The Major shrugged. “Well, it’s treacherous, there’s no doubt of it. But the only way to avoid it is to travel over the Pole, which would lose us days and offer us no guarantee of volcanoes on the Brightside—even on the Darkside, though But there were problems of atmosphere on Brightside, as flow from Brightside to Darkside. Not much—the lighter gases had reached escape velocity and disappeared from Brightside other heavier gases. There was also an abundance of sulfur vapor, as well as carbon disulfide and sulfur dioxide. The atmospheric tide moved toward the Darkside, where it condensed, carrying enough volcanic ash with it for Sanderson to estimate the depth and nature of the surface upheavals on Brightside from his samplings. The trick was to find a passage that avoided those upheavals as far as possible. But in the final analysis, we were barely scraping the surface. The only way sleepy, almost indolent, but capable of abrupt alertness. like this, and some of the best wouldn’t seem to be the most getting to that.” He settled back in his chair and continued. We jumped off from Twilight on a course due southeast with thirty days to make it to the Center of Brightside. If we could cross an average of seventy miles a day, we could hit Center exactly at perihelion, the point of Mercury’s closest approach to the Sun—which made Center the hottest part of the planet at the hottest it ever gets. The Sun was already huge and yellow over the horizon that Sun would grow bigger and whiter, and every day the was to meet us on the other side in the Laboratory’s scout ship, approximately sixty days from the time we jumped off. That was the plan, in outline. It was up to us to cross those dragging the sledges, so we’ll have to direct your course pretty closely. Peter’s job is to pick the passage at any given point. If there’s any doubt of safe passage, we’ll all explore ahead on foot before we risk the Bugs. Got that?” doesn’t matter. I just feel better when I’m on the move. Does never forget that huge yellow Sun glaring down, without a break, hotter and hotter with every mile. We knew that the first few days would be the easiest and we were rested and fresh when we started down the long ragged gorge southeast of the Twilight Lab. Major and McIvers crawling out behind me, their pillow tires taking the rugged floor of the gorge smoothly. Behind them, the track the early research teams had made out into the edge of Brightside. But in a couple of hours we rumbled past Sanderson’s little outpost observatory and the tracks stopped. We were in virgin territory and already the Sun was beginning to that glaring Sun and the baked yellow rocks going past, and The sun-shield cut the temperature down sixty or seventy with a barely visible yellowish mist of sulfur and sulfurous the hardest way possible: overland, through anything the land could throw up to us, at the most difficult time possible. worse heat in the Solar System was the surface of the Sun itself. Brightside was worth trying for. We would get it or it would get us. That was the bargain. The gorge petered out after a hundred miles and we moved onto the slope of a range of ragged craters that ran south and face of the planet. Not enough for erosion, though. The craters rose up out of jagged gorges, huge towering spears of rock and rubble. Below were the vast yellow flatlands, smoking and hissing from the gases beneath the crust. Over everything was gray ash, filling crevices and declivities—offering a soft, treacherous

<question>:
What is the Brightside?

<options>:
A The Brightside is the side of Mercury that constantly faces the sun.
B The Brightside is the first passage to the core of Vulcan Crater on Venus.
C The Brightside is the name of the passage on the Andean mountains of Venus.
D The Brightside is the name of the crossing the climbers are going to climb.

<answer>:

A