Explain the concept of urbanization.

Urbanization refers to the growth and expansion of cities as more individuals migrate from rural areas to urban environments. This process is typically driven by various factors such as the search for better employment opportunities, enhanced access to education and healthcare, and the appeal of urban lifestyle and amenities. As people move into cities, they contribute to the population increase, which often results in economic development, changes in infrastructure, and cultural transformations within urban settings.

Urbanization can lead to significant social and environmental changes, as cities become more densely populated and develop diverse economies. This growth can also present challenges, such as overcrowding, environmental degradation, and the need for improved public services. The concept encompasses not just the physical expansion of cities but also the societal shifts that occur as urban populations grow and change over time.

Other options suggest reversals of urbanization or shifts towards smaller settlements, which do not accurately define the primary trend observed in urbanization. Instead, the focus is fundamentally on the movement and concentration of people in urban areas, making the correct definition crucial for understanding global demographic trends.