The correct answer is: a) District.
A district is an administrative division of a country or state, larger than a municipality or county and usually smaller than a province or state. Districts are often divided into sub-districts or talukas.
In Odisha, there are 30 districts. The districts are further divided into sub-divisions, blocks, and gram panchayats.
A sub-division is an administrative division of a district. It is headed by a sub-divisional officer (SDO).
A block is an administrative division of a district. It is headed by a block development officer (BDO).
A gram panchayat is a village council. It is the lowest level of government in India. It is headed by a sarpanch.
The district is the highest level of administrative division in Odisha because it is the largest administrative division in the state. The district is responsible for providing a range of services to the people living in the district, including education, healthcare, and infrastructure.