The black soil of the Deccan Plateau is more related to which rock base?

Correct answer: Basaltic lava rocks

The governing concept is the relationship between parent rock, weathering, and soil formation. Much of the black soil, or regur, of the Deccan Plateau developed from the weathering and decomposition of basaltic lava flows associated with the Deccan Trap. Basalt supplies clay-rich minerals and contributes to the soil's dark colour and moisture-retaining character. Therefore option B is correct. Coral rocks and marine sand are coastal materials, while glacial deposits are associated with formerly glaciated areas and do not explain the extensive Deccan black-soil belt. The answer follows the parent-material connection between basaltic lava and regur soil.