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.

[Q]: Which property of proteins best allows them to perform an enormously diverse range of functions?  
 (A) their large, chemical-energy reserve (B) their large, stored-electric potential (C) the complexity of their folded structure (D) the wide variety of elements they include
[A]: C


[Q]: 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
[A]: C


[Q]: What is true of mutualistic relationships among organisms?  
 (A) The organisms ignore each other. (B) The organisms cooperate with each other. (C) The organisms prey on each other. (D) The organisms compete with each other.
[A]:
B