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.

[EX Q]: 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
[EX A]: B

[EX Q]: Which object is best used to demonstrate the bending of light as it passes through a substance?  
 (A) convex lens (B) flat mirror (C) opaque rod (D) concave mirror
[EX A]: A

[EX Q]: A group of students are observing a fish tank for a school assignment. The group is to share the observations with the class. Which statement about observations is true?  
 (A) Observations should always be recorded. (B) Observations should be collected only once. (C) Observations are only collected by scientists. (D) Observations are always correct if used in a chart.
[EX A]:
A