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.
--------
Question: In some locations, squirrels sleep for long periods of time during the winter months. Which of the following most likely causes these squirrels to sleep for long periods of time?  
 (A) increase in humidity (B) decrease in temperature (C) clouds forming in the sky (D) winds blowing in the night

Answer: B


Question: While conducting an experiment on gravity, what will be needed to ensure the safety of students?  
 (A) quiet zones (B) drop zones (C) heavy objects (D) frictionless surfaces

Answer: B


Question: When water changes from a liquid to a gas and then the steam condenses back to the liquid form, these types of changes are  
 (A) physical. (B) chemical. (C) electrical. (D) mechanical.

Answer:
A