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.

Q: What is the MAJOR reason Earth has seasons?  
 (A) Earth has a moon (B) Earth has a tilted axis (C) Earth has a magnetic field (D) Earth has an elliptical orbit

A: B
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Q: Which human organ system eliminates liquid and gaseous wastes from the body?  
 (A) circulatory (B) endocrine (C) excretory (D) reproductive

A: C
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Q: All metabolic functions fall into one of two categories: a breaking down process (catabolic) or a building up process (anabolic). Which is an example of an anabolic process?  
 (A) respiration (B) protein synthesis (C) oxygen transport (D) carbohydrate digestion

A:
B
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