TASK DEFINITION: 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.
PROBLEM: 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

SOLUTION: C

PROBLEM: Which of these senses lets Dora know when a skunk has been close to her house?  
 (A) Taste (B) Touch (C) Smell (D) Hearing

SOLUTION: C

PROBLEM: Because sulfur cannot be decomposed by simple chemical methods into two or more different substances, it is classified as  
 (A) an element. (B) a compound. (C) a mixture. (D) a molecule.

SOLUTION:
A