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: In some locations, squirrels sleep for long periods of time during the winter months. Which of the following most likely causes these squirrels to sleep for long periods of time?  
 (A) increase in humidity (B) decrease in temperature (C) clouds forming in the sky (D) winds blowing in the night
Example Output: B

Example Input: A light-year is a measure of  
 (A) time. (B) energy. (C) distance. (D) direction.
Example Output: C

Example Input: Carbon cycles through several Earth subsystems. Which sequence most directly leads to the cycling of carbon that can result in the formation of petroleum?  
 (A) biosphere to lithosphere (B) atmosphere to lithosphere (C) hydrosphere to atmosphere (D) biosphere to atmosphere
Example Output:
A