Step 1: Understanding the question:
The question asks which Indian city is known as the country's financial capital.
Step 2: Key fact:
Mumbai hosts India's principal financial institutions, the Reserve Bank of India, the Bombay Stock Exchange and the National Stock Exchange, and the headquarters of most major banks and corporations, earning it the title 'financial capital of India.'
Step 3: Why other options are wrong:
New Delhi is the political/administrative capital; Kolkata and Chennai are major regional/commercial hubs but do not hold the 'financial capital' designation.
Final Answer:
Mumbai (option ii).