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:
In order to maintain good health, humans should  
 (A) eat foods high in fat (B) exercise regularly (C) drink alcohol often (D) smoke tobacco occasionally

Ex Output:
B


Ex Input:
A scientist combines oxygen and hydrogen to form water. This combination illustrates that water is  
 (A) an atom. (B) an element. (C) a mixture. (D) a compound.

Ex Output:
D


Ex Input:
Which of the following is the best example of a wave?  
 (A) a stone rolling downhill (B) a vehicle traveling on a bumpy road (C) a string vibrating on a guitar (D) a grasshopper jumping up and down occasionally

Ex Output:

C