Answer:
D) thriving forest
Step-by-step explanation:
-A desert is a big area with sand that has no vegetation.
-An ocean is a large body of water.
-A shallow sea is a body of salt water that has little depth.
-A forest is an ecosystem that has a lot of vegetation.
According to the definitions and considering that the fossils found are comprised of ferns and trees, the answer is that the environment was a thriving forest.