The correct option is C Bengal, Bihar and Orissa
Exp—After the Battle of Buxar in 1764, in which Mir Qasim (Nawab of Bengal), Shuja-ud-Daulah (Nawab of Awadh) and Shah Alam II (Mughal Emperor). They got defeated by britisher(EIC) and they signed two humiliating treaties of Allahabad ( 12 august and 16 august 1765) and as a result, the company got the Diwani of Bengal, Bihar and Orissa in 1765. The company could now collect the revenue.