Correct Option :
D. I and III
Statement I is correct. The term "megacity" generally refers to an urban agglomeration with a population exceeding 10 million people. However, in the Indian context, the Ministry of Urban Development has sometimes used a threshold of 5 million for specific schemes and classifications, particularly in earlier definitions or for statistical purposes. Given the options, and the common understanding of major Indian urban centers, cities like Mumbai, Delhi, Kolkata, Chennai, Bengaluru, and Hyderabad fit this criterion, having populations well over 5 million.
Statement III is correct. Many of India's megacities serve as either national or state capitals. For instance, Delhi is the national capital, while Mumbai (Maharashtra), Kolkata (West Bengal), Chennai (Tamil Nadu), and Bengaluru (Karnataka) are state capitals. This dual role often contributes to their growth and status as major urban centers due to administrative, economic, and political functions.
Incorrect Options:
Statement II is incorrect. While some Indian megacities are significant seaports (e.g., Mumbai, Kolkata, Chennai), not all of them are. For example, Delhi, Bengaluru, and Hyderabad are prominent megacities but are landlocked and do not function as seaports. Therefore, the assertion that "All the megacities are important seaports" is factually inaccurate.