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.

[EX Q]: Which of the following units best represents the density of an object?  
 (A) kg (B) hr (C) m/s^2 (D) g/cm^3
[EX A]: D

[EX Q]: Which of these is a renewable resource found in Nevada?  
 (A) zinc metal (B) gravel deposits (C) petroleum products (D) geothermal energy
[EX A]: D

[EX Q]: Which action is an example of an exothermic process?  
 (A) baking bread (B) cooking an egg (C) making ice cubes (D) evaporation of water
[EX A]:
C