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: In gym class a student kicks a soccer ball high into the air. As the ball goes upward, which type of energy is increasing?  
 (A) kinetic energy (B) thermal energy (C) potential energy (D) mechanical energy
Example Output: C

Example Input: Which would be the best method to use to dispose of cardboard boxes not utilized by a local grocery store?  
 (A) burn them once a month (B) send them to be dumped in a remote area (C) have them recycled for future paper products (D) put them into a dumpster with the rest of the trash
Example Output: C

Example Input: Which of these gases, on average, has the lowest volume in the atmosphere of Earth?  
 (A) oxygen (B) nitrogen (C) water vapor (D) carbon dioxide
Example Output:
D