You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

Example Input: A geologist finds a layer of shale near the surface from a certain time period. Nearby, the geologist finds the same layer of shale, but it is deeper underground than the first layer. What might have caused the difference in the depth of the shale layer?  
 (A) a meteorite (B) a fault (C) ancient fossils (D) animal life
Example Output: B

Example Input: Planets in the solar system are in constant motion. What factor has the greatest effect on the orbits of the planets?  
 (A) the size of the planets (B) gravitational pull of the Sun (C) the composition of the planets (D) electromagnetic radiation from the Sun
Example Output: B

Example Input: What best describes objects orbiting in the Kuiper Belt?  
 (A) metallic (B) rocky (C) hot (D) icy
Example Output:
D