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]: Which statement describes animal embryos?  
 (A) display all the features of an adult (B) represent the earliest stage of development (C) have the same number of cells as a fertilized egg (D) have half the number of chromosomes as an adult
[EX A]: B

[EX Q]: A teacher breaks a bar of pure copper into two different sized pieces. Which is the most likely difference between the two pieces?  
 (A) mass (B) texture (C) boiling point (D) melting point
[EX A]: A

[EX Q]: To study the effect of heat on plant growth, Andy divided ten identical seedlings into groups. She placed one group on a windowsill in the sun and the other group in a dark closet on the cool (north) side of the house. Think about the characteristics of a properly designed scientific experiment. What is wrong with the above experiment?  
 (A) The temperature difference between the two groups was not great enough. (B) The amount of light was different for the two groups. (C) One group of seedlings got less water than the other. (D) Nothing is wrong with the experiment.
[EX A]:
B