Delhi, Mumbai, Kolkata and Bengaluru have high concentration of population due to which of the following reason(s) ?

All of the above

The correct answer is Option 4: All of the above

Delhi, Mumbai, Kolkata, and Bengaluru have very high concentration of population due to several combined factors:

• Industrial development creates employment opportunities.
• Urbanisation leads to the growth of cities and better facilities.
• Rural-urban migration increases population as people move to cities in search of jobs, education, and better living conditions.

NCERT: The urban regions of Delhi, Mumbai, Kolkata, Bengaluru, Pune, Ahmedabad, Chennai and Jaipur have high concentration of population due to industrial development and urbanisation drawing a large number of rural-urban migrants which also leads to addition to population.