Option a is the correct answer. The founder of Visistadvaita Siddhanta was Ramanujacharya. He was a 11th-12th century philosopher and the main proponent of Vishishtadvaita philosophy, which is a school of Hindu philosophy belonging to the Vedanta tradition1. Vishishtadvaita means "non-duality with distinctions" or "qualified monism" and it upholds the belief that all diversity ultimately stems from a fundamental underlying unity. Ramanujacharya wrote commentaries on the Brahma-sutras, the Bhagavadgita, and the Upanishads, and he identified a personal God (Vishnu) with the brahman, or Absolute Reality, of the Vedanta. He also taught that liberation (moksha) is attained by a life of exclusive devotion (bhakti) to God, who in turn offers his grace to the devotee.