The correct answer is: c) Progressive rulers.
Banganapalle was a princely state in the Indian subcontinent, which existed from the 17th century to 1948. It was ruled by the Nawabs of Banganapalle, who were a Muslim dynasty. The Nawabs were known for their progressive rule, and they introduced many reforms to the state, including education, healthcare, and infrastructure. They also built many palaces and other buildings in the state.
The other options are incorrect. Option (a) is incorrect because Banganapalle was not known for its diamond mines. Option (b) is incorrect because Banganapalle was not known for its irrigation projects. Option (d) is incorrect because Banganapalle was not known for its forest resources.