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:
Air is composed of many different substances. Which of the following components of air is a compound rather than an element?  
 (A) Argon, Ar (B) Oxygen, O2 (C) Water, H2O (D) Nitrogen, N2

Ex Output:
C


Ex Input:
Two atoms of oxygen combine to form pure oxygen gas. What is the electrical charge of the O_{2} molecules?  
 (A) positive (B) negative (C) neutral (D) variable

Ex Output:
C


Ex Input:
A new moon occurs about every  
 (A) day. (B) year. (C) week. (D) month.

Ex Output:

D