If the rock samples obtained are in the order A-B-C-D from top to the bottom then fossil found in layer B has more similarity to fossil in layer A than layer D.
Explanation:
To estimate the age of fossil we try to determine the age of rock from where the fossil was obtained. The deeper the rock layer, older the fossil would be. Here in the question the most deepest layer of rock is D which means the fossil remains obtained here would be the oldest and can be considered as the ancestor of other the fossils obtained in the layers above it.
The top most layer is A, which is the most recent layer and would contain fossil remains of most recently fossilized animal. Fossils obtained from adjacent layers are expected to have more similarities than the ones obtained from distant layers. Since rock layer B is more closer to A, it will have the fossils with more similarities to fossils in layer A than in layer D.
