Explanation:

- In 1765, the Mughal emperor appointed the British East India Company as the Diwan of the provinces of Bengal, Bihar, and Orissa. This appointment gave the Company significant administrative control, allowing them to collect revenue and manage the region's economy.

- Option 1, 1770: This date is not associated with the appointment as Diwan, though it is a period marked by economic challenges and the Bengal famine.

- Option 2, 1754: This predates the Battle of Plassey (1757), which significantly impacted British dominance in India.

- Option 3, 1750: Occurs before any significant British power establishment in Bengal from the Battle of Plassey onwards.