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: A boy pulls a sweater off over his head. His hair is attracted to the sweater due to  
 (A) a magnetic force (B) a heat transfer (C) a chemical change (D) an electrical charge

Answer: D


Question: A student tosses a ball into the air. Which force causes the ball to fall back to the ground?  
 (A) gravity (B) magnetism (C) mechanical (D) friction

Answer: A


Question: Which of these provide the best evidence that life could develop on Mars?  
 (A) its atmospheric gases (B) its surface temperatures (C) its craters and rocky surface (D) its ice and organic molecules

Answer:
D