The Peshwa is the correct answer. The Peshwa was the chief minister of the Maratha Empire and held significant authority. In the Third Anglo-Maratha War, the Peshwa took the initiative to organize a confederacy of Maratha chiefs against the English.

Let`s discuss the other options to understand why they are not the correct answer:

Option 2: Sindhia - Sindhia was one of the prominent Maratha chiefs, but he did not take the initiative in organizing the confederacy against the English.

Option 3: Holkar - Holkar was another powerful Maratha chief, but he also did not take the initiative for organizing the confederacy.

Option 4: Gaekwad - Gaekwad was the ruler of the Baroda state, but he, too, did not lead the initiative to organize the confederacy against the English.

Therefore, the Peshwa, as the chief minister of the Maratha Empire, played a crucial role in forming the confederacy of Maratha chiefs and leading them against the English in the Third Anglo-Maratha War.