The correct answer is - D. Shantytowns and squatter neighborhoods have sprung up, housing millions of people and often lacking water, electricity, and proper sanitation.
The rapid urbanization in Mexico and Brazil hasn't been going as planned at all. Millions of people from the rural areas and smaller towns have flooded the big cities, but the amount of people coming in was not corresponding with the planned urbanization, so the peripheries of the large cities never managed to be built properly. Because of this millions of people leave in poverty, the infrastructure is either bad or lacking, and basic stuff for living are often limited. So instead of development and prosper this places have to offer only poverty and struggle to survive.