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]: On a field trip, a student holds a frog and reports that it has slippery skin. This is an example of  
 (A) a measurement (B) a prediction (C) an explanation (D) an observation
[EX A]: D

[EX Q]: Strong winds have the ability to uproot large trees in a wooded area. Which of these organisms would most likely benefit from this change in a habitat?  
 (A) a bee colony that needs a hive (B) a bird that needs to build a nest (C) a squirrel that needs to find shelter (D) a plant that needs sunlight to grow
[EX A]: D

[EX Q]: A student placed a small chip of limestone into a hydrochloric acid solution, and carbon dioxide gas was released. The carbon dioxide provided evidence that   
 (A) only a physical change occurred. (B) a chemical change occurred. (C) only a loss of mass occurred. (D) the formation of an element occurred.
[EX A]:
B