In this task, you are given two facts, and a multiple-choice question. Based on the given facts, answer the question with index of the correct option (e.g, "A").

Fact1: being burried under soil and mud changes peat into coal through extreme heat and pressure in a swamp over a long period of time, Fact2: Swamp vegetation was compressed to form coal., Question: What is compressed into coal over long periods of time? (A) an object (B) bottom of feet (C) energy (D) carbon dioxide (E) rays or beams (F) kinetic energy (G) electricity (H) vegetation
H