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 Input:
Planets in the solar system are in constant motion. What factor has the greatest effect on the orbits of the planets?
(A) the size of the planets (B) gravitational pull of the Sun (C) the composition of the planets (D) electromagnetic radiation from the Sun

Ex Output:
B

Ex Input:
In a lab investigation, a student notes that two metal blocks have the same mass. Based on this observation, if the two blocks were put on opposite sides of a balance, they would best represent
(A) balanced forces. (B) unbalanced forces. (C) equal and opposite reactions. (D) objects in motion.

Ex Output:
A

Ex Input:
Which sentence describes a characteristic of offspring produced by sexual reproduction?
(A) The offspring have half the amount of genetic material as the parents. (B) The offspring contain genetic material from both parents. (C) The female offspring contain only genes from the mother. (D) The male offspring contain only genes from the father.

Ex Output:
B