Question: Coal is solid rock that began as organic material that was deposited in a swamp. The formation of coal suggests that

What is the correct answer to the question from the following choices?
Options:
[A]. coal is made mostly of skeletal remains of animals.;
[B]. coal is formed from magma that has solidified over time.;
[C]. it quickly becomes petrified when water is removed.;
[D]. geologic processes continue over millions of years.;
[D].