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 is a major difference between the life cycles of different types of plants?  
 (A) the way they die (B) the energy they use (C) the way they reproduce (D) the way they make food
Example Output: C

Example Input: The systems of the human body work together. Which system works with the skeletal system by pulling on the bones to create movement?  
 (A) digestive (B) circulatory (C) muscular (D) nervous
Example Output: C

Example Input: Fossil fuels were formed from  
 (A) uranium (B) sea water (C) sand and gravel (D) dead plants and animals
Example Output:
D