Correct Option (D)
Statement I is correct. The United Nations defines a megacity as an urban agglomeration with a population exceeding 10 million people. However, in the Indian context, the Census of India defines a megacity as a city with a population of 5 million or more. Examples include Mumbai, Delhi, Kolkata, Chennai, Bengaluru, and Hyderabad.
Statement III is correct. Most of India's megacities serve as either national or state capitals. Delhi is the national capital. Mumbai is the capital of Maharashtra, Kolkata is the capital of West Bengal, Chennai is the capital of Tamil Nadu, Bengaluru is the capital of Karnataka, and Hyderabad is the capital of Telangana. This concentration of administrative functions contributes to their growth and status.
Incorrect Options:
Statement II is incorrect. While some Indian megacities are significant seaports (e.g., Mumbai, Kolkata, Chennai), not all megacities hold this distinction. For instance, Delhi, Bengaluru, and Hyderabad are major inland megacities and do not function as seaports. Therefore, the assertion that all megacities are important seaports is factually inaccurate.