Correct Option: C

Ujjain is a birth place of Brahmagupta. By the 6th century BC, Avanti with its capital at Ujjaini, is mentioned in Buddhist literature as one of the four great powers along with Vatsa, Kosala and Magadha. Ujjain lay on the main trade route between North India and Deccan going from Mathura via Ujjain to Mahismati (Maheshwar) on the Narmada, and on to Paithan on the Godavari, western Asia and the West.