Option d is the correct answer. Buddhaghosa was a Sri Lankan Buddhist monk and scholar who lived in the 5th century CE. He is considered to be one of the most important figures in the development of Theravada Buddhism. Buddhaghosa's most famous work is the Visuddhimagga, or "The Path of Purification". It is a comprehensive manual on Theravada Buddhist doctrine and practice. Important Tips Nagarjuna: He was a Buddhist philosopher who lived in the 2nd century CE. He is considered to be one of the founders of Mahayana Buddhism. Padmasambhava: He was a tantric Buddhist guru who lived in the 8th century CE. He is credited with introducing tantric Buddhism to Tibet. Vasubandhu: He was a Buddhist philosopher who lived in the 5th century CE. He is considered to be one of the founders of the Yogacara school of Mahayana Buddhism.