The correct answer is: Caves and rock shelters.
Early hunter-gatherer communities in Goa likely lived in caves and rock shelters because these were the most readily available and easily defensible places to live. Caves and rock shelters provided protection from the elements, wild animals, and other human groups. They were also relatively easy to find and access, which was important for hunter-gatherers who were constantly on the move.
Permanent villages along rivers would have been more difficult to build and maintain, and would have been less defensible than caves and rock shelters. Fortified hilltop settlements would have been even more difficult to build and maintain, and would have been less accessible to the resources that hunter-gatherers needed. Nomadic camps on the coast would have been more exposed to the elements and to other human groups, and would have been less secure than caves and rock shelters.
In addition to providing shelter, caves and rock shelters also offered a number of other advantages for early hunter-gatherers. They could be used as storage areas for food and other supplies, and they could also be used as places to conduct religious ceremonies or other important rituals.
Caves and rock shelters are still used by some hunter-gatherer communities today, particularly in remote areas where other types of housing are not available.