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.

Q: 22 Sandy is conducting an investigation to find out which food his dog likes best. Which is the manipulated variable in his investigation?  
 (A) The color of his dog's food dish (B) The kind of food he gives his dog (C) The amount of food he gives his dog (D) The time of day he feeds his dog

A: B
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Q: Because water can hold a large amount of heat, which effect do oceans have on nearby land areas?  
 (A) They prevent rapid extreme temperature changes. (B) They form high-pressure areas that cause magma currents. (C) They provide the energy that triggers volcanic events. (D) They lower the freezing point of fresh water.

A: A
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Q: Which of the following is a by-product of cellular respiration in animals?  
 (A) oxygen (B) heat (C) sugar (D) protein

A:
B
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