What can be determined about the top layer of sedimentary rock?
it is the oldest layer of rock.
it is the youngest layer of rock
it is always the most diverse layer.
nothing can be determined until examined and tested.

It is the youngest layer of rock.

Explanation:

The layer is the most recent; it means that the top of the rock is the younger one. When a rock forms, gradually, the older layer goes to the bottom and continuously younger layer form at the top of the rock.

From the nature of the rocks, it is known that it takes many years to form a rock. At the time of creating, older rocks go to the bottom.

So, undoubtedly, it can be said that the top layer of sedimentary rock is the younger ones.