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.

Input: Consider Input: 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.

Output: D


Input: Consider Input: What force pulls things towards the center of Earth?  
 (A) magnetism (B) gravity (C) friction (D) energy

Output: B


Input: Consider Input: The influence of the Moon on the tides on Earth is greater than that of the Sun. Which best explains this?  
 (A) The Moon is more similar in composition to Earth than the Sun. (B) The Moon has a smaller mass than Earth and the Sun. (C) The Moon has a higher density than the Sun. (D) The Moon is closer to Earth than the Sun.


Output: D