Question

what happens to soft parts of organisms when cast fossils form?
○ they decay.
○ they petrify.
○ they form carbon films.
○ they become part of the fossil.

Explanation:

When cast fossils form, the organism's hard parts create a mold first. Soft tissues lack the structural stability to be preserved in this process; they break down and decay due to environmental factors like bacteria and decomposition, leaving only the mold to be filled by sediment to form the cast. Petrification, carbon films, and soft parts becoming part of the fossil occur in other fossilization processes, not cast fossil formation.

Answer:

A. They decay.