The black cotton soil of India has been formed due to the weathering of

1. A

   brown forest soil

   Brown forest soil. A temperate forest type, not Deccan clay.

2. B

   fissure volcanic rock

   Fissure volcanic rock. Deccan Trap basalt weathers to black cotton / regur.

3. C

   granite and schist

   Granite and schist. Red/yellow soils more often.

4. D

   shale and limestone

   Shale and limestone. Different parent.

Summary. Official key is (b) fissure volcanic rock. Black cotton soil (regur) is weathered Deccan Trap basalt from fissure eruptions.