You are given a science question (hard-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]: Two pieces of the same metal are placed on a table. The pieces of metal have the same density, mass, and texture. Which characteristic must be the ONLY difference between the two samples?
(A) They have different dimensions. (B) They have different boiling points. (C) They are made up of a different type of matter. (D) They contain a different amount of matter per unit volume.
[EX A]: A

[EX Q]: Matt is a tall, eleven-year-old boy. He has a scar on his right cheek. He is intelligent and an excellent drummer. Which of his traits did he most likely inherit?
(A) his height (B) his scar on his right cheek (C) his intelligence (D) his ability to play the drums
[EX A]: A

[EX Q]: Which set of descriptions correctly states the difference between a population and a community?
(A) Population: one species in an area Community: one species worldwide (B) Population: organisms in a small area Community: organisms in a large area (C) Population: living parts of an area Community: living and nonliving parts of an area (D) Population: one type of organism in an area Community: many types of organisms in an area
[EX A]:
D