An eclipse involving the Sun, Earth, and Moon can occur A. Every year at the same time

B. Only when the planets change

C. Only when they are in a straight line

D. only every 100 years

c.

Explanation:

Those types of clipses can occur only then the Sun, Moon, and Earth line up perfectly, that is, when the line of interesection of the Earth's orbit plane and the Moon's points directly at the Sun. This is called the line of nodes. The movement of the line of nodes causes the eclipse seasons to vary from one year to the next.