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]: Some scientists have suggested that the Moon was formed when a large body struck Earth and broke off a piece of Earth billions of years ago. Which observation would best support this suggestion?  
 (A) The rocks of the Moon are older than Earth rocks. (B) The Earth has free standing water, but the Moon does not. (C) The Earth and the Moon are gravitationally locked together. (D) The chemical composition of Moon rocks is similar to Earth rocks.
[A]: D


[Q]: Oxygen reacts with iron to produce rust and with hydrogen to produce water. Which statement describes both reactions?  
 (A) A different mixture is formed in each case. (B) A different solution is formed in each case. (C) Both a change of state and of elements is involved. (D) New molecules are formed but the same elements exist.
[A]: D


[Q]: A species of mouse spends the day sleeping in its burrow to avoid high daytime temperatures. It is processing what little water it needs from the seeds it collects. To which environment is this mouse best adapted?  
 (A) rainforest (B) marine (C) desert (D) tundra
[A]:
C