Option b is the correct answer. Amarmul is a Hindi word that means "the root of immortality". It is also the title of a book that contains the dialogues between Kabir and Dharamdas, one of his chief disciples. The book is part of the Kabir Sagar, a collection of writings attributed to Kabir and his followers. The book records the spiritual teachings of Kabir, who revealed to Dharamdas the secrets of creation, salvation, and the supreme God. The book also contains many hymns and songs composed by Kabir and Dharamdas in praise of God.