a. Brown forest soil 

b. Fissure volcanic rock 

c. Granite and schist

d. Shale and limestone 

12. Ans: b

Explanation:

The black cotton soils are also called regur. These are black cotton because cotton is the most important crop grown on these soils. These soils have been formed due to the solidification of lava spread over large areas during volcanic activity in the Deccan Plateau, thousands of years ago.

The black colour of these soils has been attributed to the presence of a small proportion of titaniferous magnetite or even to iron and black constituents of the parent rock.

Black soil is mainly found in Maharashtra, Madhya Pradesh, parts of Karnataka, Telangana, Andhra Pradesh, Gujarat and Tamil Nadu.

Hence, option b is correct.

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