Teacher: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.
Teacher: Now, understand the problem? Solve this instance: Which process is the best example of a sudden change to Earth's surface?
(A) landslides moving loose rocks downhill (B) sediments depositing on the seafloor (C) deltas forming at the mouth of rivers (D) mountains building up
Student:
A