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.

Ex Input:
The ounce, the pound, and the ton are units of  
 (A) time. (B) weight. (C) length. (D) distance.

Ex Output:
B


Ex Input:
Which body systems are most involved in the response when someone stubs his or her toe?  
 (A) nervous and muscle (B) muscle and endocrine (C) nervous and digestive (D) reproductive and circulatory

Ex Output:
A


Ex Input:
Which form of energy is produced when a rubber band vibrates?  
 (A) chemical (B) light (C) electrical (D) sound

Ex Output:

D