Q: You are given a science question (hard-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.
Which BEST describes the surface of the Earth over billions of years?
(A) A flat surface is gradually pushed up into higher and higher mountains until the Earth is covered with mountains. (B) High mountains gradually wear down until most of the Earth is at sea level. (C) High mountains gradually wear down as new mountains are continuously being formed, over and over again. (D) High mountains and flat plains stay side by side for billions of years with little change.
A:
C