How Can the Latitudinal Variation of Earth's Average Temperatures Be

How can the latitudinal variation of Earth's average temperatures be explain?

A) The curvature of Earth places the equator closest to the sun and the polar latitudes farthest from the sun.
B) The ocean moderates Earth's climate; the greatest extent of ocean is within the tropical latitudes.
C) Moist air like that found in the tropics holds more heat than the dry air of the temperate and polar latitudes.
D) Sunlight strikes the equatorial latitudes nearly perpendicularly but strikes obliquely at the temperate and polar latitudes.