Instructions: 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.
Input: Planets outside of our solar system have been detected. What suggested the presence of a planet outside of our solar system?
(A) radio wave emissions (B) a wobble in the rotation of the star (C) regular occurring eclipses of its moons (D) the discovery of a star as large as our own
Output:
B