Question

which type of fossils form from hardening sediment?
casts
tar pit fossils
carbon films
amber fossils

Explanation:

Casts form when sediment fills a mold (an impression left by an organism) and then hardens. Tar pit fossils form in tar deposits. Carbon films form when organic material is compressed and only carbon remains. Amber fossils form when organisms are trapped in tree resin that hardens.

Answer:

casts