Definition: You are given a question on astronomy. Astronomy is a natural science that studies celestial objects and phenomena. You are also given 4 answer options (associated with "A", "B", "C", "D"), out of which only one is correct. You need to answer the question by selecting the correct option. You should only answer with the choice letter, not the whole answer.
Input: Which factor s most important in determining the history of volanism and tectonism on a planet?
(A)size of the planet (B)presence of an atmosphere (C)distance from the sun (D)rotation period

A