Explanation:

• Sedimentary rocks are made due to weathering, erosion and deposition of sediments of igneous and metamorphic rocks.
• These rocks are layered rocks, so fossils are found in these type of rocks. Heat and pressure can convert the fossils of animals into petroleum and trees and plants convert into coal.
• The fossil fuel that we use is very old. We are mostly using coal and petroleum formed before 30 crore years ago in Carboniferous Period of Palaeozoic Era.

Source: NCERT