Earth's "Albedo" Is the Fraction of Radiant Energy from the Sun

Earth's "albedo" is the fraction of radiant energy from the Sun that Earth re-radiates into space. This number

A) is constant; it does not vary on a daily or seasonal basis.
B) varies as Earth rotates, but the daily variation does not change with the seasons.
C) varies with the seasons but is constant during any 24-hour rotation.
D) varies both daily and seasonally.