TASK DEFINITION: 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.
PROBLEM: What property is the same for each atom of an element?
(A) energy (B) mass number (C) atomic number (D) number of neutrons

SOLUTION: C

PROBLEM: A shallow container of salt water is placed in sunlight for a day. Which is the most likely result?
(A) All of the mixture will evaporate. (B) The salt will keep the water from evaporating. (C) The salt will separate from the water and float at the top of the container. (D) Only the water will evaporate and the salt will remain in the container.

SOLUTION: D

PROBLEM: A scientist designs a mathematical model of the rock cycle. The model predicts how changes in Earth processes will affect the amounts of different types of rock on Earth. Which quantity should stay the same as Earth processes change?
(A) the average rate at which Earth rotates (B) the average distance of Earth from the Sun (C) the total number of inactive volcanoes on Earth (D) the total amount of material on Earth

SOLUTION:
D