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]: Which is the best example of something that has kinetic energy?  
 (A) a rock sitting at the top of a steep hill (B) a tennis ball rolling across the court (C) a picture hanging on the wall (D) a piece of wood before it is burned
[A]: B


[Q]: Which is an example of an organism that has been selectively bred for a particular genetic trait?  
 (A) cats that eat mice (B) cows that graze on grass (C) pigs that form large herds (D) chickens that lay large eggs
[A]: D


[Q]: Astronomers have found low-energy background radiation in every part of the sky that they have studied. This radiation is taken as evidence of energy remaining from which event?  
 (A) supernovas (B) the big bang (C) collisions of galaxies (D) modern decay of unstable atoms
[A]:
B