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: Jeannie put her soccer ball on the ground on the side of a hill. What force acted on the soccer ball to make it roll down the hill?  
 (A) gravity (B) electricity (C) friction (D) magnetism

SOLUTION: A

PROBLEM: An organism's cells include organelles and a cell wall. In which taxonomic group or groups might the organism be classified?  
 (A) plants only (B) bacteria or archaea (C) plants, fungi, or protists (D) bacteria, fungi, or protists

SOLUTION:
C