Q: 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.
A model of an atom includes red marbles for electrons, green marbles for protons, and blue marbles for neutrons. All marbles have a radius of 2 cm. How could the model be changed to represent more properties of an atom?
(A) by using smaller marbles to represent electrons (B) by using two marbles to represent each neutron (C) by using two differently colored marbles for protons (D) by switching the colors of the marbles
A:
A