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 of these will most likely harm a habitat?  
 (A) planting trees (B) water pollution (C) rainfall (D) sunlight
Example Output: B

Example Input: Which best describes a scientific theory?  
 (A) It is still being tested. (B) It is true, once written. (C) It is different for each continent. (D) It is determined in a court of law.
Example Output: A

Example Input: Mr. Mendoza's class studied different body systems. What is an important function of the circulatory system?   
 (A) providing structural support to muscles (B) carrying oxygen to cells (C) getting energy from food (D) sending messages to the brain
Example Output:
B