Option a is the correct answer. Pundravardhan Bhukti, named after the Pundra people, was located in North Bengal. This territorial division of ancient Bengal developed over time, initially based on the Pundra tribe but gradually evolving into a significant political and religious center. During the Gupta period, it became an important bhukti (territorial division) with various districts and subdivisions. It extended from the Padma River in the south to the Himalayas in the north and expanded its jurisdiction during the Pala period to include areas beyond North Bengal, even reaching the northeastern region of Sylhet. This region played a vital role in cultural exchange and was strategically located on trade routes connecting China with Magadha. However, it faded from prominence in the medieval period when it became known as Mahasthan.