The correct answer is c) Kanyakumari.
Kanyakumari is a district in the Indian state of Tamil Nadu. It is located on the southernmost tip of mainland India, at the point where the Indian Ocean, the Arabian Sea, and the Bay of Bengal meet. The district is known for its beautiful beaches, temples, and historical sites.
The other options are incorrect because they are not located on the southernmost tip of mainland India. Malappuram is a district in the Indian state of Kerala. Ernakulam is a district in the Indian state of Kerala. Thiruvananthapuram is the capital of the Indian state of Kerala.