A traditional group dance performed by women during the festival of Onam is:

Thiruvathirakali
Margamkali
Oppana
Mohiniyattam

The correct answer is: A) Thiruvathirakali

Thiruvathirakali is a traditional group dance performed by women during the festival of Onam in Kerala, India. It is a ritual dance that is performed to celebrate the homecoming of the mythical King Mahabali. The dance is performed in a circle, with the women holding hands and swaying their bodies to the rhythm of the music. The dance is accompanied by songs that tell the story of Mahabali.

Margamkali is a traditional dance form of Kerala that is performed by both men and women. It is a martial art dance that is performed to the accompaniment of drums and cymbals. The dance is characterized by its intricate footwork and its use of weapons.

Oppana is a traditional dance form of Kerala that is performed by women. It is a folk dance that is performed to the accompaniment of songs and music. The dance is characterized by its lively and energetic movements.

Mohiniyattam is a classical dance form of Kerala that is performed by women. It is a dance that is based on the story of the Hindu goddess Mohini. The dance is characterized by its graceful and elegant movements.