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.
Q: Which observation provides evidence of the existence of planets orbiting other stars?
(A) periodic dimming of the stars (B) periodic X-ray bursts from the stars (C) rapid location changes of the stars (D) regular spectrum changes from the stars
A:
A