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: Compost piles have many parts, such as leaves, moisture, vegetables, and microorganisms. Which part of a compost pile breaks down materials and adds nutrients to the soil?  
 (A) leaves (B) moisture (C) vegetables (D) microorganisms

Output: D


Input: Consider Input: Which type of organism is at the lowest level of the food chain?  
 (A) autotroph (B) heterotroph (C) carnivore (D) omnivore

Output: A


Input: Consider Input: Which of these questions is best answered by observing the habitat of an insect?  
 (A) How much does an insect weigh? (B) How long does an insect live? (C) When does an insect breed? (D) Where does an insect live?


Output: D