a) Inverted arch foundation
b) Floating foundation
c) Mat foundation
d) Grillage foundation

Answer: c
Explanation: Black cotton soil is clay or loose type of soil and is considerably swells and shrinks by variation in moisture content. The variation in the volume of the soil is to the extent of 20 to 30% of the original volume. Hence, Raft Foundation or Mat Foundation plays important role in uniform distribution of a load of structure over black cotton soil.