Respuesta :
It would be D, I believe, a scarcity of land to spread out and so instead they are building up, the other answers don't make sense because building skyscrapers infer the opposite of scarcity about A, B and C. Hope that helps! :D :)
The correct answer is D.
Vertical urbanization models are more common in European capitals and large cities, rather than the construction of buildings of 2-3 floors and the creation of wider cities (which is more the case in the US). Such European cities are able to house more people by using tall buildings so that each piece of land is inhabited by a larger amount of individuals. Population density is larger due to the lack of land resources.