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 of the following units best represents the density of an object?
(A) kg (B) hr (C) m/s^2 (D) g/cm^3
[A]: D

[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
[A]: A

[Q]: Which of the following best explains why the tectonic plates of Earth move?
(A) conduction from solar heating (B) heat convection from the mantle (C) global winds (D) ocean currents
[A]:
B