The correct answer is option 4: Port Blair. The Mahatma Gandhi National Marine Park is located in Port Blair, which is the capital city of the Andaman and Nicobar Islands in India. The Marine Park was established to protect the marine biodiversity and conservation of marine life in the region.
Option 1, Pirotan Island, is incorrect as Pirotan Island is located in the Gulf of Kutch in Gujarat, not in Port Blair.
Option 2, Rameswaram, is also incorrect as Rameswaram is a town in Tamil Nadu, located on Pamban Island and does not have the Mahatma Gandhi National Marine Park.
Option 3, Ganga Sagar Island, is incorrect too, as Ganga Sagar Island is an island in the Sundarbans delta, located in West Bengal, and does not house the Mahatma Gandhi National Marine Park.
Therefore, the correct answer is option 4, Port Blair. Alert - correct answer should be Port Blair.