Poompuhar was an ancient port city of the:

The correct answer is: a) Cholas.

Poompuhar was an ancient port city of the Cholas. It was located on the east coast of India, in the present-day state of Tamil Nadu. The city was founded in the 3rd century BC and flourished for over a thousand years. It was a major center of trade and commerce, and was also known for its temples and palaces. The city declined in the 13th century, due to a combination of factors, including attacks by foreign invaders and the silting up of its harbor. However, it remains an important archaeological site, and its ruins are a popular tourist destination.

The other options are incorrect because:

• The Pandyas were a Tamil dynasty that ruled over southern India from the 6th to the 13th centuries. They were based in Madurai, and their capital was known as Madurai.
• The Pallavas were a Tamil dynasty that ruled over southern India from the 3rd to the 9th centuries. They were based in Kanchipuram, and their capital was known as Kanchipuram.
• The Cheras were a Tamil dynasty that ruled over southern India from the 3rd to the 13th centuries. They were based in Uraiyur, and their capital was known as Uraiyur.