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: How does sedimentary rock form?  
 (A) sediments cool (B) sediments melt (C) sediments separate (D) sediments compress
Example Output: D

Example Input: Which material is the best conductor of electricity?  
 (A) Wood (B) Metal (C) Stone (D) Plastic
Example Output: B

Example Input: Unequal distribution of the hormone auxin in plants helps to regulate the direction of plant growth. Which of the following is accomplished by plants in regulating the distribution of auxin?  
 (A) pollination of flowers (B) transportation of nutrients (C) discouraging predation (D) responding to the environment
Example Output:
D