Detailed Solution:
The correct answer is “Mumbai is the most populous metropolis of India.”.
1) According to the Census of 2011, about 70% of the total Indian population reside in villages, while 30% reside in urban areas.
2) The year 1921 is called "The Great Divide" in India because the time India has "Low rate of mortality and High rate birth".
3) Around 21 million people live in Mumbai, which makes it the most populated city in India and the third-most populous city in the world.
4) India's Uttar Pradesh state has 7 cities with a population size of 1 million or more. - Kanpur > Lucknow > Ghaziabad > Agra > Meerut > Varanasi > Prayagraj.