Tamil Nadu is prone to cyclones, primarily forming in the:

The correct answer is: b) Bay of Bengal

The Bay of Bengal is a semi-enclosed tropical sea located between India to the west, Myanmar and Bangladesh to the north, the Andaman and Nicobar Islands to the east, and Sri Lanka and the Maldives to the south. It is connected to the Indian Ocean to the south by the Palk Strait and the Gulf of Mannar, and to the Andaman Sea to the east by the Strait of Malacca.

The Bay of Bengal is a major cyclone basin, with an average of 4-5 cyclones forming each year. The most severe cyclones can cause widespread damage and loss of life.

The Bay of Bengal is also a major fishing ground, and is home to a variety of marine life, including dolphins, whales, and turtles.

The other options are incorrect because:

• The Indian Ocean is a much larger body of water, and cyclones can form in any part of it. However, the Bay of Bengal is a particularly active cyclone basin.
• The Arabian Sea is a smaller body of water, and cyclones are less common there.
• The Pacific Ocean is the largest body of water on Earth, and cyclones can form in any part of it. However, the Pacific Ocean is not as active a cyclone basin as the Bay of Bengal.