The correct answer is: b) Block
A block is the primary administrative unit for revenue collection in Odisha. It is a sub-division of a district and is headed by a Block Development Officer (BDO). The BDO is responsible for the implementation of government schemes and programs in the block, as well as for the collection of revenue.
A sub-division is an administrative unit that is smaller than a district. It is headed by a Sub-Divisional Magistrate (SDM). The SDM is responsible for the maintenance of law and order in the sub-division, as well as for the collection of revenue.
A tehsil is an administrative unit that is smaller than a sub-division. It is headed by a Tehsildar. The Tehsildar is responsible for the collection of revenue in the tehsil, as well as for the maintenance of land records.
A gram panchayat is a village-level self-government institution in India. It is the smallest unit of local government in the country. Gram panchayats are responsible for a variety of functions, including the provision of basic amenities, such as water, sanitation, and education, as well as the maintenance of law and order.