The Kongu dialect of Tamil is primarily spoken in and around the region of:

The correct answer is c) Coimbatore.

The Kongu dialect of Tamil is primarily spoken in and around the Coimbatore region. It is a distinct dialect of Tamil with its own unique features, such as a different pronunciation of certain words and a different grammar structure. The Kongu dialect is spoken by about 10 million people in India.

The other options are incorrect because they are not regions where the Kongu dialect is primarily spoken. Madurai is a city in the Madurai district of Tamil Nadu, India. Thanjavur is a city in the Thanjavur district of Tamil Nadu, India. Chennai is the capital of the Indian state of Tamil Nadu.