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 student examines a new watch design. The watch has a small solar cell on its face. The main function of the solar cell is to  
 (A) reduce the cost of the watch. (B) provide an energy source for the watch. (C) make the watch more attractive. (D) stop the watch from speeding up.
Example Output: B

Example Input: Which of these properties of water helps moderate the weather of coastal areas?  
 (A) neutral pH (B) high specific heat (C) dissolves many substances (D) floats as a solid
Example Output: B

Example Input: In large industrial cities, the emissions from fossil fuels cause the atmosphere to change. Which process allows the atmosphere to change?  
 (A) increased inorganic matter in soil (B) increased use of fertilizers on crops (C) increased buildup of greenhouse gases (D) increased rainfall rates near power plants
Example Output:
C