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.
--------
Question: Which of the following is an example of a behavioral adaptation?  
 (A) hooves of a horse (B) migration of birds (C) a spider web (D) a bee hive

Answer: B


Question: 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

Answer: D


Question: Neurons respond to stimuli and transmit impulses to coordinate body functions. Which of these indicates the rapid change in the membrane potential when a neuron is stimulated?  
 (A) action potential (B) resting potential (C) refractory period (D) threshold period

Answer:
A