The correct answer is: a) Dimapur.
Dimapur is the most populous district in Nagaland, with a population density of 1,177 people per square kilometer. It is the commercial and economic hub of the state, and is home to the state’s largest airport and railway station.
Kohima is the capital of Nagaland, and is the second most populous district in the state. It has a population density of 832 people per square kilometer.
Tuensang is the third most populous district in Nagaland, with a population density of 223 people per square kilometer. It is located in the northeastern part of the state, and is home to a number of tribal villages.
Mokokchung is the fourth most populous district in Nagaland, with a population density of 194 people per square kilometer. It is located in the central part of the state, and is home to a number of historical sites.