The correct option is B His commander in chief Mir Jafar joined with the forces of Robert Clive
The Battle of Plassey was a decisive victory of the British East India Company over the Nawab of Bengal and his French allies in 1757. Siraj-ud-daulah had asked Britishers to stop fortification which became one of the reasons for the war. Robert Clive bribed Mir Jafar, commander-in-chief of Siraj-ud-daulah of making him the next Nawab which resulted in betrayal from Mir Qasim and victory of the British.