Concept:Visuddhimagga is a foundational Theravada Buddhist treatise.Explanation:It was written by Buddhaghosa in Sri Lanka around 430 CE.The text is also known as 'The Path of Purification'.Nagarjuna, Padmasambhava, and Vasubandhu belong to other Buddhist traditions.Hence, Buddhaghosa is the author.Answer:Buddhaghosa (Option D).