Shale is a common type of sedimentary rock in which oil forms because A. silt and clay trap organic material as they are deposited. B. boulders squeeze the water out of leaves. C. Shale has nothing to do with oil formation. D. gravel traps organic material as it's deposited.

A.

Explanation:

Shale is a sedimentary rock that is often associated with oil deposits. This is due in part to the tiny and very fine grains that make up shale. As the sediments are compacted, organic matter is trapped by the particles of clay and silt.

Later, as sedimentation continues and the layers are buried farther underground, the heat and pressure convert some of the organic material into oil. While much of the gas escapes the porous shales, some also remains trapped in the rock layer.