Which of the Following Gives the Most Important Reason Why

Which of the following gives the most important reason why summers in the Southern Hemisphere are cooler than summers in the Northern Hemisphere?

A) Over 80 percent of the Southern Hemisphere is covered with water.
B) The Earth is closer to the sun in January.
C) The Earth is farther from the sun in July.
D) The sun's energy is less intense in the Southern Hemisphere.