Q: 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.
Sandstone and all other types of sedimentary rock are made up of particles. The source materials of these particles consist of
(A) fragments that broke off of older rocks. (B) magma that cooled deep below a volcano. (C) gases that condensed in the atmosphere. (D) vegetation that decayed in thick layers.
A:
A