Question

this is the layer of rock beneath the soil layers. flintstone pebbles bedrock rubble

Explanation:

The question is about identifying the layer of rock beneath soil layers. Bedrock is defined as the solid rock layer beneath soil and other surface materials. Flintstone is a type of rock but not the general term for the layer beneath soil, pebbles are small rock fragments, and rubble is broken rock/debris. So bedrock is the correct term.

Answer:

bedrock