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.

Ex Input:
Ella waves good-bye from the bus. What body system pulls on bones to let Ella wave her arm?  
 (A) muscular system (B) nervous system (C) digestive system (D) circulatory system

Ex Output:
A


Ex Input:
Which of the following best describes a role of mushrooms in ecosystems?  
 (A) capturing energy from sunlight (B) consuming living plant material (C) taking energy from animal hosts (D) breaking down dead plant material

Ex Output:
D


Ex Input:
Which system produces most of the hormones in the human body?  
 (A) circulatory (B) digestive (C) endocrine (D) respiratory

Ex Output:

C