Question: Liam lives in the Northern Hemisphere of Earth and plays in the snow in December. His friend lives in the Southern Hemisphere of Earth and plays at the beach in December. What is the best explanation for why this is possible?

  Options: 
 A. tilt of Earth on its axis
 B. rotation of Earth on its axis
 C. revolution of Earth around the Sun
 D. revolution of the Moon around Earth
Answer: A