Option d is the correct answer. Shankaradeva was a 15th-16th century saint, reformer, and founder of the Ekasarana Dharma, a monotheistic branch of Vaishnavism. He was born in Bardowa, Nagaon district of Assam, which was then part of the Ahom kingdom. He was influenced by the teachings of Ramananda and Kabir, and travelled widely across India to learn from various religious traditions. He preached devotion to a single formless God, whom he called Hari or Narayana, and identified with Vishnu and Krishna. He rejected caste distinctions, idol worship, animal sacrifice, and ritualism. He composed many devotional songs, poems, dramas, and commentaries in Assamese and Brajavali languages. Shankardeva's contributions to Assamese literature and culture: Nirvana Shatakam: This is a hymn composed by Shankardeva in which he describes the nature of enlightenment. Bhakti Ratnavali: This is a play composed by Shankardeva in which he tells the story of Krishna and Radha. Kirtan Ghosa: This is a collection of hymns composed by Shankardeva. Satriya Dharma: This is a treatise on the Satriya movement composed by Shankardeva. Important Tips Chaitanya was a 15th-16th century saint, mystic, and founder of the Gaudiya Vaishnavism, a branch of Vaishnavism that worships Krishna as the supreme personality of Godhead. Nimbarka was a 12th-13th century philosopher and founder of the Kumara Sampradaya, a branch of Vaishnavism that worships Radha and Krishna as the supreme reality. Ramananda was a 14th-15th century saint, reformer, and founder of the Ramanandi Sampradaya, a branch of Vaishnavism that worships Rama as the supreme deity. Gaudiya Vaishnavism: Gaudiya Vaishnavism originated in the Gauda region of Bengal, which is now part of West Bengal and Bangladesh. Gaudiya Vaishnavism believes in the doctrine of avatar, or divine descent, which states that God periodically incarnates in human or animal forms to restore dharma, or cosmic order. Some of the most popular avatars of Krishna are Rama, Narasimha, Vamana, and Kalki.