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]: A scientist combines oxygen and hydrogen to form water. This combination illustrates that water is  
 (A) an atom. (B) an element. (C) a mixture. (D) a compound.
[A]: D


[Q]: A student conducts an investigation using mold spores. In one part of the investigation, he needs to closely examine a spore sample. Which piece of equipment does the student need to use to keep mold spores from entering his respiratory system?  
 (A) breathing mask (B) safety goggles (C) rubber gloves (D) lead smock
[A]: A


[Q]: Earth rotates on its north-south axis. Which statement best describes one complete rotation?  
 (A) It takes six months and causes summer and winter seasons. (B) It takes 24 hours and causes night and day. (C) It takes 29 days, which represents one cycle of the Moon's phases. (D) It takes 365 days, which represents one Earth year.
[A]:
B