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]: A student plans to grow algal colonies in solutions with different concentrations of liquid fertilizer. Which is a clear and testable hypothesis to guide this investigation?  
 (A) Algae like fertilizer. (B) Fertilizer is good for algae. (C) Fertilizer improves the genetic traits of algae. (D) Algal growth rate increases with fertilizer concentration.
[EX A]: D

[EX Q]: What kind of energy conversion occurs after a candle is lit?  
 (A) friction to electrical energy (B) light energy to heat energy (C) mass to kinetic energy (D) chemical energy to light energy
[EX A]: D

[EX Q]: Improvements in geological observation technologies have made it easier for scientists to locate resources in Earth's crust. These technologies have allowed for an increase in availability of which resource?  
 (A) wind power (B) solar energy (C) fossil fuel (D) tidal energy
[EX A]:
C