Explanation: In the context of metropolitan cities in India, the term "metropolitan" refers to a large urban area that is characterized by a high population density, significant economic activity, and administrative importance. The size of a metropolitan city is often measured by the population of its urban agglomeration, which includes the city proper and its surrounding areas.
Delhi, the national capital of India, is the largest metropolitan city in the country. The urban agglomeration of Delhi, which includes the city proper and the National Capital Region (NCR), has a population of over 29 million people, making it the most populous urban agglomeration in India. This large population is a result of Delhi's role as the political, economic, and administrative center of the country, attracting people from various parts of India and beyond.
Kolkata and Chennai are also significant metropolitan cities in India, but they do not have as large an urban agglomeration as Delhi. Kolkata, located in the eastern part of India, is a major cultural and economic hub, but its urban agglomeration is smaller than that of Delhi. Similarly, Chennai, located in the southern part of India, is a major industrial and economic center, but its urban agglomeration is also smaller than that of Delhi.
It is important to note that the size of a metropolitan city is not solely determined by the population of the city proper but also by the population of the surrounding areas that are closely integrated with the city. This integration is often seen in terms of economic activities, transportation networks, and social interactions. Therefore, when considering the largest metropolitan city, one must take into account the entire urban agglomeration, not just the city itself.
In conclusion, Delhi is the largest metropolitan city in India due to its large urban agglomeration, which includes the city proper and the surrounding areas of the National Capital Region. This makes it the most populous urban agglomeration in the country, reflecting its significant role as the national capital and a major economic and administrative center.