The correct answer is: d) Gulf of Mannar.
The Gulf of Mannar is a shallow sea between the Indian state of Tamil Nadu and the island nation of Sri Lanka. It is part of the Indian Ocean. The Gulf of Mannar is a major fishing ground and is also home to a number of important coral reefs.
The Arabian Sea is a marginal sea of the Indian Ocean located to the west of India and Sri Lanka, east of the Arabian Peninsula, north of the Indian Ocean proper, and south of the Gulf of Oman and the Persian Gulf.
The Bay of Bengal is an extension of the Indian Ocean located between India to the west, Myanmar (Burma) to the north, Bangladesh to the east, and Sri Lanka to the southeast.
The Indian Ocean is the third largest ocean in the world, covering an area of about 70 million square kilometers (27 million square miles). It is bounded by Africa to the west, Asia to the north, Australia to the east, and Antarctica to the south.