What is the capital city of India?

The capital city of India is New Delhi. As the seat of government, New Delhi hosts the President's residence, the Parliament, and the Supreme Court of India, making it a central hub for political activities in the country. Designed in the early 20th century by British architect Edwin Lutyens, New Delhi is distinct from the larger metropolis of Delhi and has been the capital since India gained independence in 1947.

Understanding this context highlights New Delhi's significance as a political and administrative center, and it stands out distinctly from the other listed cities. Islamabad is the capital of Pakistan, Bangkok is the capital of Thailand, and Kolkata is one of the largest cities in India but serves as the capital of the state of West Bengal, not the entire country. Thus, New Delhi's role and status as the official capital solidify its position as the correct answer.