Vishnu Narayan Bhatkhande is remembered for which contribution to Hindustani music?

The correct answer is B, classifying ragas under ten thaats. Bhatkhande travelled across India collecting compositions and then arranged the ragas of Hindustani music under ten parent scales or thaats, among them Bilawal, Kalyan, Khamaj, Bhairav, Kafi, Asavari, Bhairavi and Todi. He also set down a system of notation and wrote at length on the practice of the music, which is why the classification carries his name.

Option A is wrong because the Pancharatna Kritis, the five gem compositions, were written by Tyagaraja in the Carnatic tradition. Option C is wrong because the pakhawaj is an old barrel drum with no single named inventor, and certainly not a nineteenth-century scholar. Option D is wrong because the Gwalior gharana is the oldest khayal gharana and long predates him. Remember Bhatkhande alongside Vishnu Digambar Paluskar, his contemporary, who did most to bring the music out of private patronage and into public schools and concerts.