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 location on Earth receives the most direct sunlight?  
 (A) the deserts (B) the South Pole (C) the equator (D) the Western Hemisphere
[EX A]: C

[EX Q]: Many scientists are convinced that an increase of certain gases in the atmosphere is affecting global temperatures. What makes this hypothesis difficult to prove?  
 (A) Trees absorb these gases. (B) Global temperatures are rising. (C) Many variables affect global temperatures. (D) Many human activities produce these gases.
[EX A]: C

[EX Q]: Rosa and Ted ate granola bars before competing in a swimming competition. Less than 50% of the chemical energy in the granola bars was converted to mechanical energy during the swim competition. If all the energy in the granola bars was used, which most likely happened to the rest of the energy?  
 (A) It was lost as potential energy. (B) It was lost as chemical energy. (C) It was converted to thermal energy. (D) It was converted to magnetic energy.
[EX A]:
C