The correct options are
B The Pandya and Chera dynasties were associated with late Megalithic culture.
C The Krishna-Godavari Valley region houses numerous megaliths from the Sangam age.
Till the second century BCE, the upper parts of the South Indian peninsula, which includes the Tamil regions, were inhabited by people known as megalith builders. The Chola, Pandya and Chera dynasties are associated with the late Megalithic culture. Numerous megaliths of the Sangam age have been found in the Krishna-Godavari Valley region, while a lesser number of these have been found in the southern districts of present-day Tamil Nadu. A few of the megaliths had a box-like structure made by stone slabs placed on each other without the use of mortar.