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: Where do good bacteria grow to help keep people healthy?  
 (A) in the brain (B) in the blood (C) on the skin (D) on the bones

Output: C


Input: Consider Input: What force pulls things towards the center of Earth?  
 (A) magnetism (B) gravity (C) friction (D) energy

Output: B


Input: Consider Input: Which scientist developed the mathematical models used to describe the changes in the motion of objects as well as the forces that cause the change in motion?  
 (A) Dalton (B) Newton (C) Aristotle (D) Ptolemy


Output: B