Answer:
As a result of urbanization.
Step-by-step explanation:
Urbanization is the process of transforming a society, region or territory from rural to urban, that is, it represents not only the growth of the population of cities, but the increase of this in relation to the inhabitants of the countryside. Therefore, when the urban population of a given place grows larger than that of the countryside, we say that a process of urbanization is occurring. In the process, city dwellers had to buy food at their wages because they could no longer grow their own crops to consume or trade for other resources. Similarly, people had to pay rent for housing because they could no longer trade their services for shelter.