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: The systems of the human body work together. Which system works with the skeletal system by pulling on the bones to create movement?  
 (A) digestive (B) circulatory (C) muscular (D) nervous

Output: C


Input: Consider Input: Which of the following is the main role of flowers found on most flowering plants?  
 (A) to take in air (B) to produce seeds (C) to absorb nutrients (D) to protect the stem

Output: B


Input: Consider Input: Betsy tries to attract a variety of birds to her backyard. She puts up a bird feeder that contains sunflower seeds and corn. Which term best describes the contents of the bird feeder?  
 (A) a mixture (B) a solution (C) an element (D) a compound


Output: A