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: One substance found on Earth is more stable as an elemental gas than as part of a solid compound. As a result, this substance is very abundant in the atmosphere. Which substance exhibits these traits?  
 (A) argon (B) chlorine (C) nitrogen (D) oxygen

SOLUTION: C

PROBLEM: Which of these cycles takes 24 hours?  
 (A) Earth rotating on its axis (B) Earth revolving around the Sun (C) the Moon rotating on its axis (D) the Moon revolving around Earth

SOLUTION: A

PROBLEM: Mosquitoes have adapted to detect carbon dioxide using certain sensory nerves. Mosquitoes instinctually move toward greater concentrations of carbon dioxide. What is the importance of this adaptation?  
 (A) It helps mosquitoes find food. (B) It helps mosquitoes find mates. (C) It helps mosquitoes find clean air. (D) It helps mosquitoes find shelter.

SOLUTION:
A