Science help!

When populations become so dense as to cause overcrowding, there is an increase in the rate of infectious diseases within the population. This is because overcrowding usually leads to a(n)

Adecrease in available medical care.
Bincrease in the amount of wealth of the population.
Cincrease in quality of living conditions and sanitation.
Ddecrease in quality of living conditions and sanitation.

Verified Answer :

A or D... depending on which country you are talking about and if it is a developed or developing country...
the effects of overcrowding will definitely be negative...
sorry not much help!