In which Indian state did the Baul tradition of wandering mystic singers develop most prominently?

The correct answer is West Bengal.

Step 1: Understanding the Baul Tradition
The Bauls are a renowned group of wandering mystic minstrels whose philosophy and music represent a unique blend of Vaishnava Hinduism, Sufi Islam, and Tantric traditions. They express their spiritual beliefs through soulful folk songs accompanied by simple musical instruments like the eiktara (one-stringed instrument), dotara, and dubki.

Step 2: Geographical and Cultural Origin
The Baul tradition developed most prominently in the Bengal region, which encompasses present-day West Bengal in India and neighboring Bangladesh. Within West Bengal, districts such as Birbhum, Nadia, and Murshidabad are historically known as major hubs for Baul music and culture. The annual Joydeb Kenduli Mela in the Birbhum district of West Bengal is one of the most famous gatherings where Bauls assemble to perform.

Step 3: Global Recognition
Recognizing its deep cultural significance and profound philosophical message of universal love and humanism beyond caste and religion, UNESCO included the Baul tradition in its list of the Masterpieces of the Oral and Intangible Heritage of Humanity in 2005.

Conclusion:
Hence, West Bengal is the Indian state where the Baul tradition of wandering mystic singers developed most prominently.