The famed Kimmeridge soil that covers Chablis' Grand Crus is noted for containing limestone, clay, and what else?

The correct answer is associated with the unique composition of Kimmeridge soil, which is renowned in the Chablis region for its mineral richness and distinctiveness. This soil type is particularly rich in fossilized oyster shells, a characteristic feature that contributes to the terroir of the area.

Fossilized oyster shells are remnants of marine life from the Jurassic period and play a significant role in the soil's ability to retain moisture and drain well, which is essential for vine health. The presence of these shells also adds to the complexity of flavors in the wines produced in Chablis, allowing them to express a unique mineral character.

The other options like granite, slate, and sandstone do not form part of the Kimmeridge soil's profile and thus are not relevant to its classification or the characteristics that influence the winemaking in the Chablis region.