You are given a science question (hard-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]: During an investigation, heat transferred from a liquid to the environment. Which pair of explanations can best account for this result?  
 (A) The temperature of the liquid increased, or the liquid became a gas. (B) The temperature of the liquid increased, or the liquid became a solid. (C) The temperature of the liquid decreased, or the liquid became a gas. (D) The temperature of the liquid decreased, or the liquid became a solid.
[EX A]: D

[EX Q]: Which is the most likely reason that using energy generated from wind is better for air quality than burning fossil fuels?  
 (A) the equipment for harnessing wind is inexpensive (B) wind produces less pollution than fossil fuels (C) energy from wind power is easy to store (D) wind is more efficient than fossil fuels
[EX A]: B

[EX Q]: Suppose a new fuel for cars is derived from coal. Cars can go twice as far on a tankful of the new fuel as they can on the same amount of gasoline. How would you categorize the new fuel?  
 (A) It is a renewable fossil fuel. (B) It is a nonrenewable fossil fuel. (C) It is a renewable biomass fuel. (D) It is a nonrenewable biomass fuel.
[EX A]:
B