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.

Example Input: Which of these statements about nonrenewable resources is true?  
 (A) They are inexpensive. (B) They help keep the air clean. (C) They can take millions of years to form. (D) They are used because they are easily removed from the ground.
Example Output: C

Example Input: Kim lost her hammer outside. When she found it a few months later, some parts of the metal were covered with flaky, brown rust. Which type of change occurred when rust formed on the hammer?  
 (A) chemical (B) electrical (C) thermal (D) physical
Example Output: A

Example Input: Ocean tides result mainly from  
 (A) surface winds. (B) radiant heat from stars. (C) Earth's tilt on its axis. (D) the Moon's gravitational pull.
Example Output:
D