Which of the following best describes a densely populated area usually found in cities?

A densely populated area typically found in cities is best described as an urban center. Urban centers are characterized by high population densities, with greater concentrations of people living and working in close proximity. This is often due to economic opportunities, access to services such as education and healthcare, and the availability of infrastructure and public transport.

In contrast, rural zones refer to areas outside towns and cities, which tend to have lower population densities and are often dominated by natural landscapes or agricultural land. Suburban districts are residential areas situated on the outskirts of urban centers, usually featuring lower population densities than urban areas but more than rural zones. Exurban areas extend even further out from the urban core, attracting populations looking for more space, often resulting in even lower densities compared to urban and suburban zones. Thus, the urban center is the most appropriate description for a densely populated area within a city.