The Rise of Complex Civilizations in the Nile, Indus, and Tigris

The rise of complex civilizations in the Nile, Indus, and Tigris and Euphrates River valleys led to which of the following?

A) a rise in the spread of disease and a series of ecological disasters resulting from over-farming and human efforts to reshape their landscapes
B) a decrease in the incidence of disease as humans invented better technologies and medicines
C) the development of cultural uniformity among the three river civilizations as they came into increased contact with one another
D) the disappearance of all foraging societies, as they could not compete with the successes of organized agriculture and urban complexes