The correct options are
B He supported the amalgamation of Bhajans and Keertans.
C He belonged to the Varkari sect.
D There was involvement of taal instruments in his Bhajans.
Sant Namadev was a poet, scholar, and devotee of Lord Vithala. He is credited with being the first Keertankar. Keertankars usually perform in temples or in the precincts of temples. Keertans make use of instruments like the harmonium, mridangam, and the taal. He supported the amalgamation of Bhajans and Keertans, and popularised it through the Varkari sect. In the Varkari Keertan, the involvement of the taal musicians is important.