The correct answer is (d). The Marathas learnt the art of guerilla warfare from their own experience. They were a small and relatively weak kingdom, and they needed to find a way to fight against the larger and more powerful Mughal Empire. Guerilla warfare was a perfect way for them to do this, as it allowed them to use their knowledge of the local terrain and their small numbers to their advantage.
Mahabat Khan was a Mughal general who fought against the Marathas. He was a skilled military commander, but he was not the one who taught the Marathas the art of guerilla warfare.
Man Singh was a Rajput general who fought for the Mughal Empire. He was a skilled military commander, but he was not the one who taught the Marathas the art of guerilla warfare.
Malik Amber was a Turkoman general who fought for the Mughal Empire. He was a skilled military commander, but he was not the one who taught the Marathas the art of guerilla warfare.