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]: When iron combines with oxygen in a moist environment, rust forms because of a
(A) chemical reaction. (B) physical reaction. (C) change in density. (D) change in temperature.
[A]: A

[Q]: All of the planets in the solar system formed at about the same time from a large cloud of gas and dust. How is Earth different from other planets in the solar system?
(A) Earth has no natural satellites. (B) Earth's atmosphere is composed of gases. (C) Water is found in all three phases on Earth. (D) Volcanoes release liquid rock onto Earth's surface.
[A]: C

[Q]: After a race, a newspaper lists the names of the five fastest runners. Another method that could be used to identify the five fastest runners is to make a chart that shows the
(A) average of the speeds of the runners. (B) total distance for each runner. (C) time it took each runner to run the race. (D) percentage of the runners who finished the race.
[A]:
C