Explanation:

- The Battle of Plassey occurred on 23 June 1757, between Siraj ud-Daulah and the British East India Company. Siraj ud-Daulah was the Nawab of Bengal, and the battle marked a significant turning point in Indian history as it laid the foundation for British rule in India.

- Option 1: 15 September 1765 - This date does not relate to the Battle of Plassey. It is several years after the battle and doesn’t correlate with a major event in Plassey.

- Option 2: 21 June 1780 - This date is much later and irrelevant to the context of the Battle of Plassey.

- Option 3: 25 May 1745 - This date is too early, predating the battle by over a decade.