Hint: Mumbai is the capital city of India's state Maharashtra. A group of individuals of the same species living and interbreeding within a given area is defined as population. In the given question you have to find the correct option which relates the question very well.
Complete answer: Option A) 11 Million :- Mumbai is the most populated city in India. It's city population is estimated to be more than 11 millions. Hence, this will be the incorrect option to be opted. Option B) 18 Million :- It is not the correct option to be opted as it is not the correct estimation of the population. Option C) 125 Million :- It is not the correct option to be opted as it is not the correct estimation of the population. Option D) None of these :- It is the correct option to be opted as the estimation of the population of greater mumbai is near about 20 million as per the Census 2011.
Hence, option D is the correct option to be opted.
Note: Here, are some points related to the city Mumbai: Mumbai is the most populated city in India. It's city population is estimated to be near about 20 millions. Mumbai has the highest number of millionaires and billionaires among all cities of India. Mumbai is also named as Bombay. Population growth causes a disproportionate negative impact on the environment. Problems of population size and growth, resource utilization and depletion, and environmental deterioration must be considered jointly and on a global basis.