In which one of the following districts, have large reserves of diamond-bearing kimberlite been discovered in the recent past?

Answer: (b) Raipur

Kimberlite pipes were found in Raipur district (Payalikhand, Behradin).

The idea

Kimberlite is a volcanic rock that can carry diamonds from great depth. A diamond-bearing pipe is a geological occurrence, not automatically a producing mine. District names must be read as of the question year because later administrative divisions can change them.

Diamond crystals form at depth → Rising magma picks up some crystals → Magma reaches shallow levels rapidly → A volcanic pipe forms → Sampling tests diamond content → Economics decides whether mining is viable

Why the others are wrong

(a) Hoshangabad is in MP — no kimberlite find.

Also know

Payalikhand and Behradih were described under the old Raipur district in the 2007 context. Panna–Majhgawan is a separate diamond anchor in Madhya Pradesh. Wajrakarur in Andhra Pradesh is another pipe-field association; kimberlite and lamproite should not be treated as identical rock names.