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: Which property of air does a barometer measure?  
 (A) speed (B) pressure (C) humidity (D) temperature

A: B
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Q: In an accurate diagram of the solar system, which object would be shown closest to Earth?  
 (A) the Moon (B) the asteroid belt (C) Mars (D) Saturn

A: A
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Q: A balloon filled with helium gas is set free and starts to move upward. Which of the following best explains why the helium balloon moves upward?  
 (A) The density of helium is less than the density of air. (B) The air resistance lifts the balloon up. (C) There is no gravity acting on the helium balloons. (D) The wind blows the balloon upward.

A:
A
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