Why is coal referred to as a fossil fuel?

a.

coal was formed from decaying layers of plants in swamps millions of years ago. they fossilized into coal.

b.

coal was formed from marine organisms millions of years ago. they fossilized into coal.

c.

coal was formed from black shales that were uplifted millions of years ago and fossilized into coal.

d.

coal was formed from marine sediments millions of years ago. they compacted and cemented into coal.