Fossils in layers of rock are generally estimated to be fossils found in the deeper layers a. older, younger b. newer, younger c. older, older d. newer, older science btw

Your answer is (B.)
Fossils in newer layers if rock are generally estimated to be younger than fossils found in the deeper layers because it is closest to the surface. The soil and earth didn't have enough time to "bury" the remains of the dead animal ( Bury is used for a simpler term) underground. The farther down a fossil is the more likely it is older unless the animal tends to burrow. Seeing as the question is probably talking of older animals that is unlikely for an animal to burrow that far. So your answer is B.

I'm pretty sure the answer is B.

Digestion because it removes waste