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: Which force produces energy as heat?  
 (A) pull (B) gravity (C) friction (D) magnetic

Output: C


Input: Consider Input: Which two body systems maintain the level of glucose in the blood?  
 (A) nervous and respiratory systems (B) digestive and endocrine systems (C) muscular and immune systems (D) skeletal and cardiac systems

Output: B


Input: Consider Input: Which of the following causes a chemical change?  
 (A) sugar added to soda (B) detergent added to water (C) lemon juice added to milk (D) salt added to water


Output: C