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]: An object such as a hammer weighs less on the Moon than on Earth. This is because the Moon has a
(A) thinner atmosphere than Earth. (B) smaller diameter than Earth. (C) stronger magnetic field than Earth. (D) lower mass than Earth.
[EX A]: D

[EX Q]: Earth is composed of layers of material with different properties. Which of the following is most likely to be in constant motion?
(A) core (B) mantle (C) oceanic crust (D) continental crust
[EX A]: B

[EX Q]: Solids that are combined together and maintain their physical properties are best labeled as a
(A) solute. (B) mixture. (C) solvent. (D) compound.
[EX A]:
B