_____ is made up of small lumps of rocks with cracks and crevices.

• The third layer of soil is made up of small lumps of rocks with cracks and crevices. This layer is called C- Horizon. 
•  A-horizon- It is dark in colour and is rich in humus and many minerals.
•  B-horizon- It contains less humus, soluble minerals, and organic matter. It is a site of deposition of certain minerals and metal salts such as iron oxide.
•  Bedrock- Bedrock is the common term for solid rock under the surface of the earth.

Hence, the correct answer is C-Horizon.