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: Which of these statements about nonrenewable resources is true?  
 (A) They are inexpensive. (B) They help keep the air clean. (C) They can take millions of years to form. (D) They are used because they are easily removed from the ground.
Example Output: C

Example Input: Which is the best example of evaporation?  
 (A) raindrops freezing (B) an ice cube melting (C) a puddle drying in the sun (D) a sponge soaking up water
Example Output: C

Example Input: The theory of plate tectonics provides the current explanation for the way in which  
 (A) stars change. (B) continents move. (C) rocks are formed. (D) tides are produced.
Example Output:
B