Correct Answer: (a) Kannauj
Note: During the post-Gupta period, the business centre was shiftted to Kannauj from Ujjain During Gupta period, the importance of Ujjain was increased as Chandragupta-II made it second capital. During post-Gupta period, Harsha made Kannauj as capital in place of Thaneswar. As Kannauj was situated on the bank of Ganga and Jamuna, it was the place of business importance and became the centre of attraction for three powers (Palas, Pratiharas and Rashtrakutas).