What is the main reason for the porous nature of the Bhabar region?

Correct answer: Pebbles and coarse deposits

The direct answer is B, pebbles and coarse deposits. Bhabar is a narrow belt along the Himalayan foothills where rivers deposit large pebbles, gravel and other coarse material. The spaces between these large particles are open, so river water often disappears underground. Step by step: Himalayan streams carry stones; the slope decreases; coarse material is deposited; gaps remain between the particles; water sinks through those gaps. Option A, fine marine clay, is not the characteristic material of Bhabar. Option B is correct because coarse, porous alluvial deposits create the open texture. Option C, coral limestone, is associated with coral formations and is not the main Bhabar deposit. Option D, black lava soil, develops from basaltic volcanic rock and is not typical here. Memory cue: Bhabar means boulders, gravel and sinking streams.