The correct answer to the question is option 1: First Maratha War.

The Treaty of Salbai was signed in 1782 between the Maratha Empire and the British East India Company. It marked the end of the First Anglo-Maratha War which took place from 1775 to 1782.

Option 2: Second Maratha War is incorrect. The Second Anglo-Maratha War took place from 1803 to 1805 and ended with the Treaty of Bassein.

Option 3: Third Maratha War is incorrect. The Third Anglo-Maratha War occurred from 1817 to 1818 and resulted in the defeat of the Marathas by the British.

Option 4: Fourth Mysore War is incorrect. The Fourth Anglo-Mysore War took place from 1798 to 1799 and did not involve the Marathas. It was primarily a conflict between the British East India Company and the Kingdom of Mysore.

To summarize, the Treaty of Salbai concluded the First Maratha War, not any of the other wars mentioned.