Here's why:

* Sediment size classification: Sedimentary rocks are classified based on the size of the particles they are made from.

* Clay size range: Clay particles are defined as being smaller than 0.0039 cm (0.0015 inches) in diameter.

Therefore, a sedimentary rock formed from 0.0002 cm sediment would be classified as a claystone or shale. These rocks are known for their fine-grained texture and often exhibit layering (lamination).