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]: A scientist combines oxygen and hydrogen to form water. This combination illustrates that water is  
 (A) an atom. (B) an element. (C) a mixture. (D) a compound.
[A]: D


[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 numbat, a small Australian marsupial, requires fallen logs and dead trees for shelter and for its primary food, termites. Loss of old-growth forests containing logs and dead trees could threaten the numbat with extinction. What would be the best method to protect the numbat from extinction?  
 (A) provide feeding stations with termites for the numbats (B) protect areas of old-growth forest from clear-cutting (C) prohibit hiking in forests where numbats live (D) move the numbat to a different habitat
[A]:
B