The Chennai Music Season is a major annual event celebrating:

Carnatic music
Tamil film music
Folk music
Western classical music

The correct answer is: a) Carnatic music.

Carnatic music is a classical music tradition that originated in southern India. It is one of the oldest surviving musical traditions in the world, and is characterized by its complex melodies, rhythms, and harmonies. The Chennai Music Season is a major annual event that celebrates Carnatic music, and attracts musicians and music lovers from all over the world.

Tamil film music is a genre of film music that is popular in the Indian state of Tamil Nadu. It is characterized by its use of Carnatic music, folk music, and Western music. Tamil film music is often used in Tamil films, and is also popular as a form of independent music.

Folk music is a genre of music that is typically passed down orally from generation to generation. It is often associated with a particular region or culture, and can be characterized by its use of simple melodies, rhythms, and harmonies. Folk music is often used in traditional ceremonies and celebrations.

Western classical music is a genre of music that originated in Europe in the Middle Ages. It is characterized by its use of complex melodies, rhythms, and harmonies. Western classical music is often performed in concert halls, and is also popular as a form of background music.