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 energy source is considered nonrenewable?  
 (A) moving water (B) fossil fuel (C) wind (D) biomass
[A]: B


[Q]: What is the function of the nucleus in a cell?  
 (A) provides energy (B) provides nutrients (C) controls activity (D) controls movement
[A]: C


[Q]: Proteins are compounds formed in the cells of plants and animals. Which element is included in every protein molecule?  
 (A) calcium (B) carbon (C) fluorine (D) sodium
[A]:
B