The correct answer is: A. Sakyas
The Buddhist sources like Mahavamsa and Dipavamsa describes Chandragupta Maurya as a scion of the Sakya clan. The Sakyas were a clan of the Gautama gotra, which was a branch of the Kshatriya varna. The Sakyas were a powerful clan in the region of Kapilavastu, which is now in Nepal. The Buddha, Siddhartha Gautama, was born into the Sakya clan.
The Haryankas were a clan of the Kuru janapada. The Kurus were a powerful clan in the region of Kurukshetra, which is now in Haryana. The Mahabharata is set in the Kurukshetra War between the Pandavas and the Kauravas, who were both branches of the Kuru clan.
The Puravas were a clan of the Yadu janapada. The Yadavas were a powerful clan in the region of Mathura, which is now in Uttar Pradesh. The Krishna, one of the most important figures in Hinduism, was born into the Yadava clan.
The Pandyas were a clan of the Chola janapada. The Cholas were a powerful clan in the region of Tamil Nadu. The Mahabharata mentions the Pandyas as one of the five major powers in India at the time.
In conclusion, the Buddhist sources like Mahavamsa and Dipavamsa describes Chandragupta Maurya as a scion of the Sakya clan.