Which of the following best describes how the interaction of the Sun, moon and Earth result in the lunar cycle? Light from the sun -
A. always illuminates half of the Moon, but we see different portions of the lit half as relative positions change.
B. illuminates different amounts of the Moon's surface as the distance between the Sun and Moon changes.
C. illuminates the entire surface of the Moon at all times, but looks different because of Earth's shadow.
D. reaches only parts of the Moon not blocked by clouds, which shrink and grow over time.