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: In an accurate diagram of the solar system, which object would be shown closest to Earth?  
 (A) the Moon (B) the asteroid belt (C) Mars (D) Saturn

Answer: A


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: Which discovery was necessary before radio could be invented?  
 (A) reflection (B) radiation (C) electricity (D) gravity

Answer:
C