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

<passage>:
ALL DAY SEPTEMBER "That's fine! That's just line! Is Evans—?" "Can't tell yet. They spotted the tractor from the satellite observatory. Captain Jones took off a few minutes ago, and he'll report trying—when it's time to give up because it's hopeless.... The meteor, a pebble, a little larger than a match head, traveled through space and time since it came into being. The light from the star that died when the meteor was created fell on Earth before the first lungfish ventured from the sea. In its last instant, the meteor fell on the Moon. It was impeded by It was two days to sunrise, where Evans stood. It was just before sunset on a spring evening in September in Sydney. The shadow line between day and night could be seen from the Moon to be drifting across Australia. Evans, who had no watch, thought of the time as a quarter after Australia. followed a stampede to Yellow Crater, where he thought for a while that he had a fortune in chromium. The chromite petered out in a month and a the first landing on the Moon. on the Moon!" dark again, and the search for him, if it ever began, could not begin position. "Batteries must be dead," he told himself. curved reflector that was positioned to radiate the heat of the steam into the cold darkness of space. When the meteor pierced the turbine, the sun shone as brightly as though there were no sun. They might have appeared to waver slightly, if they were behind outflung corona flares. If they did, no one noticed. No one looked toward the sun without dark filters. When Director McIlroy came into his office, he found it lighted by the rising sun. The light was a hot, brilliant white that seemed to pierce the darkest shadows of the room. He moved to the round window, screening his eyes from the light, and adjusted the polaroid shade to maximum density. The sun became an angry red brown, and the room was dark again. Mrs. Garth was simply the first four hours after waking. on the Moon for another week. "Has the power crew set up the solar furnace?" he asked. The solar furnace was a rough parabola of mirrors used to focus the sun's heat on anything that it was desirable to heat. It was used mostly, from sun-up to sun-down, to supplement the nuclear power plant. "They went out about an hour ago," she answered, "I suppose that's what they were going to do." sure it will be to everyone's satisfaction." "I know this seems like a silly question. What day is this?" "Mrs. Garth," he called, "what day is this?" day ." "I don't know, I'll call the observatory." There was a pause. "They say what day where?" she asked. "Greenwich, I guess, our official time is supposed to be Greenwich Mean Time." There was another pause. "They say it's September fourth, one thirty a.m. " "Well, there you are," laughed McIlroy, "it isn't that time doesn't mean rate," he said. The power crew was having trouble with the solar furnace. Three of the nine banks of mirrors would not respond to the electric controls, and one bank moved so jerkily that it could not be focused, and it Nobody answered. They could all see the Moon under their feet. Small craters overlapped and touched each other. There was—except in the places that men had obscured them with footprints—not a square foot that didn't contain a crater at least ten inches across, there was not a square inch without its half-inch crater. Nearly all of these had been made millions of years ago, but here and there, the rim of a crater covered part of a footprint, clear evidence that it was a recent one. exploring when the meteor hit. Inside, he lifted his filter visor, and found that the light reflected from the small ray that peered into the across." All of these needed water to form, and their existence on the Moon type of rock was ice, frozen in a niche that had never been warmed by the sun. The sun rose to the meridian slowly. It was a week after sunrise. The stars shone coldly, and wheeled in their slow course with the sun. Only Earth remained in the same spot in the black sky. The shadow line crept around until Earth was nearly dark, and then the rim of light appeared on the opposite side. For a while Earth was a dark disk in a thin halo, and then the light came to be a crescent, and the line of dawn began to move around Earth. The continents drifted across the dark disk and into the crescent. The people on Earth saw the full moon set about the same time that the sun rose. to the Moon about once a month, carrying supplies in and metal and ores have to fight the union and the Lunar Trade Commission." charging the same rate to go either way when it takes about a seventh of the fuel to get from here to Earth as it does to get from there to half. Can't you get in touch with him by radio?" "He isn't carrying one. Most of the prospectors don't. They claim that a radio that won't carry beyond the horizon isn't any good, and one that will bounce messages from Earth takes up too much room." "Well, if I don't see him, you let him know about the chromium." "Anything to help another Welshman, is that the idea?" Slainte mhor, bach. " [Great Health, man.] The sun was halfway to the horizon, and Earth was a crescent in the sky when Evans had quarried all the ice that was available in the cave. The thought grew on him as he worked that this couldn't be the only such resolved not to leave the tractor again, and reluctantly abandoned his plan to search for a large bubble. The sun stood at half its diameter above the horizon. The shadows of the mountains stretched out to touch the shadows of the other mountains. The dawning line of light covered half of Earth, and Earth turned beneath it. Cowalczk itched under his suit, and the sweat on his face prickled his forehead against the faceplate of his helmet and rubbed off some of the sweat. It didn't help much, and it left a blurred spot in his "All clear," he heard Cade report through the intercom. "Light is off now," Cade said. PROSPECTOR FEARED LOST ON MOON IPP Williamson Town, Moon, Sept. 21st. Scientific survey director the Moon in search of minerals was due two days ago, but it was oxygen runs out. Search parties have started from Williamson Town, but telescopic search from Palomar and the new satellite observatory are hindered by the fact that Evans is lost on the part of the Moon which is now dark. Little hope is held for radio contact with the missing man as it is believed he was carrying only short-range, intercommunications equipment. Nevertheless, receivers are ... "Well, yes," Jones answered. "I thought that it might happen that a rocket would be needed in the search." The light from Earth lighted the Moon as the Moon had never lighted Earth. The great blue globe of Earth, the only thing larger than the stars, wheeled silently in the sky. As it turned, the shadow of sunset crept across the face that could be seen from the Moon. From full Earth, as you might say, it moved toward last quarter. The rising sun shone into Director McIlroy's office. The hot light formed a circle on the wall opposite the window, and the light became "Wake up, Mr. McIlroy," she said, "you told me to wake you at sunrise, minutes back. Nothing to report and the sun was rising there. Australia will be in position pretty soon. Several observatories there. Then Capetown. There are lots of observatories in Europe, but most of them are clouded over. Anyway the satellite observatory will be in position by the time Europe is." McIlroy was fully awake. He glanced at Phelps and wondered how long it It was three hours later that McIlroy woke Phelps.

<question>:
How do moon inhabitants tell the time of day?

<options>:
A Identifying the shadow line as it relates to Earth's continents
B Identifying the shadow line as it relates to the moon's time zones
C Identifying the shadow line as it relates to the moon's continents
D Identifying the shadow line as it relates to the Earth's time zones

<answer>:

A