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: Four objects are on a wooden ramp. Which object is most likely to roll off the ramp if it is pushed gently?  
 (A) flat eraser (B) round ball (C) bent paper clip (D) wooden cube

A: B
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Q: When oxygen combines with hydrogen, which substance is formed?  
 (A) water (B) vinegar (C) hydrochloric acid (D) hydrogen dioxide

A: A
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Q: Which best describes the role of the esophagus in digestion?  
 (A) It releases acid and mixes food. (B) It aids in absorption of nutrients from food. (C) It carries food from the mouth to the stomach. (D) It carries food from the stomach to the intestines.

A:
C
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