Option a is the correct answer. Therigatha isn't part of the old Jain writings. It's actually a book of Buddhist poems, said to be spoken by the first Buddhist monks in India around 600 BC. Important Tips Acarangasutra is a collection of Jain texts that deal with the rules and regulations for Jain monks and nuns. Sutrakritanga is a collection of Jain texts that deal with the cosmology and philosophy of Jainism. Brihatkalpasutra is a biographical work that details the life and teachings of Lord Mahavira, the 24th Tirthankara of Jainism.