In Hindustani classical music, according to Vishnu Narayana Bhatkhande, how many thaats are the origins of ragas?

Explanation

10. These 10 thaats are: Bilawal, Khamaj, Kafi, Asavari, Bhairav, Bhairavi, Todi, Purvi, Marwa, Yaman. Each thaat has a specific arrangement of whole and half steps, and ragas are derived from these thaats by using different combinations of notes, ornamentations, and emotional expressions.