Cities together with their suburbs and a population of more than 10 million people can be referred to as a "Megalopolis." 

This term is often used to describe a large, densely populated urban region that encompasses multiple cities and their surrounding areas, creating a highly interconnected and populous area. 

It is commonly used to describe regions with significant urban and suburban development and interactions. So, option 3, "Megalopolis," is the correct term for such a configuration.

THEREFORE THE CORRECT OPTION IS [3].