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 the following is most consistent with the modern theory of evolution?  
 (A) Parents pass their physical traits to their offspring; those offspring with traits that help them survive in the environment are able to reproduce. (B) Parents change their physical traits in order to survive in the environment, then those parental traits are passed to their offspring. (C) Life on this planet came from another planet far out in space. (D) Living organisms have not changed for hundreds of millions of years.
Example Output: A

Example Input: The body is made up of many systems that interact with one another. For example, the skeletal system and the muscular system work together to help the body move. Which system works with the respiratory system to distribute oxygen to the body?  
 (A) muscular system (B) digestive system (C) lymphatic system (D) circulatory system
Example Output: D

Example Input: Which of the following is found in all living organisms?  
 (A) cell (B) organ (C) organ system (D) tissue
Example Output:
A