Option b is the correct answer. Korkai, Poompuhar (also known as Kaveripattinam), and Muchiri are ancient port cities in the southern region of present-day Tamil Nadu, India. These cities are known for their historical significance and connections to maritime trade and commerce. Important Tips Korkai: Korkai was an important port city that flourished during the ancient period, particularly during the time of the Tamil Sangam literature (around 300 BCE to 300 CE ). It was located in the Thoothukudi district of Tamil Nadu. Poompuhar (Kaveripattinam): Poompuhar, also known as Kaveripattinam, is another ancient port city with a rich history of maritime trade. It was situated along the banks of the river Kaveri in Nagapattinam district of Tamil Nadu. Muchiri (Muziris): Muchiri, also known as Muziris, was an ancient port city located in present-day Kerala, near the town of Kodungallur. It was a significant trading center in the Indian Ocean trade network during the ancient and medieval periods.