Explanation:

- Option 1: The Treaty of Surat

- This treaty was signed in 1775 but did not conclude the First Anglo-Maratha War.

- It was a treaty between the British and Raghunath Rao for his claim to the Maratha throne.

- Option 2: The Treaty of Purandar

- Signed in 1776, this treaty revoked the Treaty of Surat agreements.

- It was between the British and the Maratha Empire but did not conclude the war.

- Option 3: The Convention of Wadgaon

- This convention in 1779 was a setback for the British forces during the war.

- It forced them to return territories but did not conclude the war.

- Option 4: The Treaty of Salbai

- This treaty was signed in 1782 and officially concluded the First Anglo-Maratha War.

- It restored territories and maintained peace between the British and the Marathas.