Explanations:Pongal is a significant harvest festival celebrated in Tamil Nadu, a state in southern India. The festival is celebrated over four days and marks the beginning of the Tamil month of Thai, which usually falls in mid-January. Pongal is dedicated to the Sun God, Surya, and is a celebration of the harvest season. The festival is named after the Tamil word "ponga," which means "to boil over," symbolizing the abundance of the harvest.
The four days of Pongal are known as Bhogi, Thai Pongal, Maatu Pongal, and Kaanum Pongal. Each day has its own unique customs and rituals. On the first day, Bhogi, people discard old belongings and clean their homes. The second day, Thai Pongal, is the main day of the festival, where people cook a special dish called "pongal" made of rice and lentils, which is offered to the Sun God. Maatu Pongal is dedicated to cattle, and Kaanum Pongal is a day for family gatherings and outings.
Onam, on the other hand, is a harvest festival celebrated in the state of Kerala, located in southwestern India. It is a ten-day festival that commemorates the homecoming of the mythical King Mahabali. Onam is not celebrated in Tamil Nadu, and it is not a four-day festival. Therefore, the correct answer is Pongal, which is a four-day harvest festival celebrated in Tamil Nadu.