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: A hearing aid is a small device that contains an amplifier, a battery, a microphone, and a speaker. Which part of a hearing aid functions to detect sounds in the user's environment?  
 (A) the amplifier (B) the battery (C) the microphone (D) the speaker

SOLUTION: C

PROBLEM: 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

SOLUTION: A

PROBLEM: Which of the following describes an instinctive behavior?  
 (A) a behavior that occurs only in adult fish (B) a behavior that occurs only in small mammals (C) a behavior that an animal learns how to do over time (D) a behavior that an animal is born knowing how to do

SOLUTION:
D