The correct answer is rice. Rice is the staple food crop of Tamil Nadu. It is grown in all parts of the state, but the major rice-growing areas are the Cauvery delta, the Kaveri basin, and the coastal districts. Rice is a major source of food and employment in Tamil Nadu. It is also an important export crop.
Wheat is not a major crop in Tamil Nadu. It is grown in some parts of the state, but it is not as important as rice. Wheat is a major source of food in other parts of India, such as Punjab and Haryana.
Maize is not a major crop in Tamil Nadu. It is grown in some parts of the state, but it is not as important as rice or wheat. Maize is a major source of food in other parts of the world, such as the United States and China.
Millet is not a major crop in Tamil Nadu. It is grown in some parts of the state, but it is not as important as rice, wheat, or maize. Millet is a major source of food in other parts of India, such as Rajasthan and Gujarat.