The correct answer is: B) Deccan Plateau
Ashmounds are unique circular mounds of ash that are found in the Deccan Plateau region of Karnataka. They are believed to have been formed by the burning of animal dung and other organic materials by ancient people. The ash mounds are an important archaeological site, as they provide evidence of the early human habitation of the region.
Coastal Karnataka is a region of Karnataka that is located along the Arabian Sea coast. It is a popular tourist destination, known for its beaches, temples, and wildlife sanctuaries. The Western Ghats are a mountain range that runs along the western coast of India. They are a UNESCO World Heritage Site, and are home to a variety of plant and animal life. The Northern plains are a region of India that is located north of the Vindhya Mountains. They are a major agricultural region, and are home to a large population.
Ashmounds are not found in Coastal Karnataka, the Western Ghats, or the Northern plains.