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: Solids, liquids, and gases are all different states of which of the following?  
 (A) mass (B) matter (C) weight (D) volume
Example Output: B

Example Input: Which of the following is closest to the percentage of the total water on earth that is freshwater?  
 (A) 100% (B) 90% (C) 70% (D) 3%
Example Output: D

Example Input: A cell that is unable to import substances required to process chemical energy is most likely a result of a malfunctioning  
 (A) cell membrane. (B) endoplasmic reticulum. (C) Golgi body. (D) nuclear envelope.
Example Output:
A