A famous hill station in Tamil Nadu is:

Ooty
Darjeeling
Shillong
Munnar

The correct answer is Ooty.

Ooty is a hill station in the Nilgiris district of Tamil Nadu, India. It is located in the Western Ghats mountains, at an altitude of 2,200 meters (7,200 feet). Ooty is a popular tourist destination, known for its scenic beauty, cool climate, and tea plantations.

Darjeeling is a hill station in the Indian state of West Bengal. It is located in the Himalayas, at an altitude of 2,000 meters (6,600 feet). Darjeeling is a popular tourist destination, known for its scenic beauty, tea plantations, and colonial architecture.

Shillong is the capital of the Indian state of Meghalaya. It is located in the Eastern Himalayas, at an altitude of 1,500 meters (4,900 feet). Shillong is a popular tourist destination, known for its scenic beauty, colonial architecture, and cultural heritage.

Munnar is a hill station in the Indian state of Kerala. It is located in the Western Ghats mountains, at an altitude of 1,600 meters (5,200 feet). Munnar is a popular tourist destination, known for its scenic beauty, tea plantations, and wildlife sanctuaries.