In India, oil is mostly found in

In India oil is found mostly in sedimentary rocks, where buried marine organic matter was transformed into hydrocarbons.

Anticlines and fault traps are structures that hold accumulated oil, but the oil itself originates in sedimentary strata.

Igneous rocks form from magma and lack the organic matter needed to generate oil.

Since sedimentary basins are the source and reservoir, the general none-of-these does not apply.

Bombay High and the Assam and Gujarat basins are all sedimentary.

Oil migrates upward until it is trapped beneath an impermeable cap rock.