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.

Input: Consider Input: What type of force keeps the planets orbiting the Sun?  
 (A) gravitational (B) magnetic (C) electrical (D) nuclear

Output: A


Input: Consider Input: Which is an example of an organism that has been selectively bred for a particular genetic trait?  
 (A) cats that eat mice (B) cows that graze on grass (C) pigs that form large herds (D) chickens that lay large eggs

Output: D


Input: Consider Input: Sound reaches our ears because sound makes air particles  
 (A) heat up. (B) cool down. (C) slow down. (D) vibrate.


Output: D