In recent decades, what relationship has developed between the number of people living in urban versus rural areas?

Answer: For the first time since the existence of the planet earth, people live more in cities and its suburbs than in rural areas.

Explanation:

In the olden days, many people lived in rural areas than the urban areas because if lack of exposure and lack access to more information. Nowadays, particular in recent decades, number of people living in the urban areas has increased significantly, and far above the rural areas, because of comfortability, availability of infrastructure, availability of basic social amenities etc people believe can be found in the urban areas.

The correct answer is:

For the first time ever, more people are living in cities and suburbs than in rural areas.

Explanation:

Currently, a major percentage of people are living in urban areas, this number has increased in the last decades.

Around the year 2000 both, urban and rural populations had an almost equal proportion with around 3 billion for each population. This number has been continuously growing for the urban populations that has reached around the 4 billion of inhabitants being this number around a 54 percent of the world's population.

So far, the rural number of inhabitants has decreased in great shape for the kind of commodities and opportunities that a person can find in the cities and also due to economic reasons.