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: The ocean minimum zone, or OMZ, is an area from 200 to 600 meters below the ocean's surface. The OMZ is dark and cold, with oxygen concentrations less than 10% of concentrations in surface water. Oxygen concentrations are so low because of bacterial activity that breaks down organic material falling from surface waters. Given the conditions in the OMZ, which of these dissolved gases would you expect to find in large concentrations in this zone?  
 (A) argon (B) nitrogen (C) carbon dioxide (D) carbon monoxide
Example Output: C

Example Input: Marta studied different forms of energy. Which two types of energy travel in waves?  
 (A) light and sound (B) electrical and sound (C) chemical and light (D) chemical and electrical
Example Output: A

Example Input: Elements on the right side of the periodic table differ from the elements on the left side in that the elements on the right side  
 (A) are solid at room temperature. (B) are good electrical conductors. (C) generally have very high densities. (D) tend to form ions by gaining electrons.
Example Output:
D