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.

Example 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
Example Output: B

Example Input: Cells come in two basic types, prokaryotic and eukaryotic. Which cell structure is found in both prokaryotic and eukaryotic cells?
(A) vacuole (B) nucleoid (C) mitochondrion (D) cytoplasm
Example Output: D

Example Input: Dalmatian dogs sometimes become deaf due to a recessive trait they may inherit. For this reason, some Dalmatian owners will not let their dogs have puppies if they are deaf. Allowing only Dalmatians that can hear to produce offspring is an example of
(A) selective breeding. (B) sexual reproduction. (C) crossbreeding. (D) learned traits.
Example Output:
A