Earth is 1 AU away from the sun. This distance stays nearly the same as Earth revolves around the sun. This is because Earth’s orbit is almost circular. Mercury’s orbit is elliptical. What does this mean in regard to Mercury’s distance from the sun?

a

Mercury follows an irregular path around the sun.

b

Mercury’s distance from the sun is always the same.

c

Mercury travels farther from the sun than Earth does.

d

Mercury’s distance from the sun varies in predictable ways.