An area with the highest growth rate of the population - Nagaland

Nagaland is correctly matched as an area with the highest growth rate of the population. The population growth rate is a measure of how fast a population is increasing over a specific period of time. Nagaland, a state in northeast India, has been experiencing a high population growth rate. This can be attributed to factors such as high birth rates, improved healthcare facilities, better living conditions, and migration from other states or regions.

An area with the lowest sex ratio - Delhi

Delhi is correctly matched as an area with the lowest sex ratio. Sex ratio refers to the number of males per 100 females in a given population. Delhi has been facing the issue of a low sex ratio for several years. This means that there are fewer females compared to males in the city. The reasons for this imbalance can be attributed to various factors like gender discrimination, cultural preferences for male children, and female feticide.

An area with the lowest density of population - Rajasthan

Rajasthan is correctly matched as an area with the lowest density of population. Population density refers to the number of people living per square kilometer of land. Rajasthan, being the largest state in India, has a relatively low population density due to its vast geographical area. It has a sparse population distribution with large stretches of desert and arid regions, resulting in a lower population density compared to other states.

An area with the highest density of population - Delhi

Delhi is correctly matched as an area with the highest density of population. Despite being a relatively small state, Delhi has a high population density. This is mainly due to factors such as rapid urbanization, migration from rural areas, job opportunities, and better infrastructure. The population density in certain areas of Delhi can be quite high, leading to overcrowding and pressure on resources and infrastructure.

In conclusion, the correctly matched options are:

(a) Area of the highest growth rate of the population - Nagaland
(b) An area with the lowest sex ratio - Delhi
(c) An area with the lowest density of population - Rajasthan
(d) An area with the highest density of population - Delhi