In how many tone scale are all the known ragas grouped?

Correct option is D

• The Melakarta system in Carnatic music uses 72 parent ragas.​
  

• The 7 shuddha swaras are: Sa, Re, Ga, Ma, Pa, Dha, Ni.

• Both Hindustani and Carnatic traditions are based on this 12-note scale.​
  

• The Thaat system in Hindustani music classifies ragas into 10 thaats​
  

• .The Thaat system was devised by Vishnu Narayan Bhatkhande.​