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: Which of the following statements best explains how the decomposition of plant and animal matter helps to form rich soils?  
 (A) Decomposition adds silt to soil. (B) Decomposition adds water to soil. (C) Decomposition adds oxygen to soil. (D) Decomposition adds nutrients to soil.

SOLUTION: D

PROBLEM: Because copper is a metal, it is  
 (A) liquid at room temperature (B) nonreactive with other substances (C) a poor conductor of electricity (D) a good conductor of heat

SOLUTION: D

PROBLEM: In order for electricity from a battery to power a light bulb, the wire has to provide the electricity a path to do what?  
 (A) flow through the entire closed circuit (B) charge the air molecules near the circuit (C) jump from one battery terminal to the other (D) change the chemical properties of the wire

SOLUTION:
A