Under the Scheduled Tribes and Other Traditional Forest Dwellers (Recognition of Forest Rights) Act, 2006, the Gram Sabha is the authority to initiate the process for determining the nature and extent of individual or community forest rights or both.
The Gram Sabha, which is the village assembly consisting of all adult members of a village, plays a crucial role in the implementation of the Act. It has the power to initiate the process of recognizing and vesting forest rights in eligible individuals and communities. The Gram Sabha identifies and recommends the claims for forest rights to the Sub-Divisional Level Committee or the District Level Committee, depending on the nature of the claim.
Therefore, the correct answer is "Gram Sabha."