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.

Leucine is one of the amino acids your body needs but cannot make. Which of these happens so that the human body can obtain leucine?  
 (A) The body converts other amino acids to leucine. (B) The body stores carbohydrates containing leucine. (C) The body breaks down fatty acids to obtain leucine. (D) The body digests protein in food to obtain leucine.
D

Which of the following is the farthest from Earth?  
 (A) Halley's comet (B) the Andromeda galaxy (C) Neptune (D) the Sun
B

Life processes require energy. Biochemical processes involve specific reactions. Which is a characteristic of biochemical processes common to all animals?  
 (A) function at any pH level (B) heat released as a product (C) use only anaerobic respiration (D) amount of energy absorbed

B

