Hi Vinod! There can be many answers to fit this blank. As of 2020, Mumbai is the 8th most populated cities in the world with a population of about 20 million. The city itself is not that large actually, but here are some words that can fill the blank if you are referring to population.
Mumbai is a very large city.
Mumbai is an extremely large city.
Mumbai is a fairly large city.
or (if you want to disagree with the size)
Mumbai is not a large city.
Hope that helps =)
