The mesoamerican mexican preclassic period is

The preclassic period covers approximately from 2500 a. C., probable date of the elaboration mainly of the first Mesoamerican pottery; until 200 d. C., in which the fall of Cuicuilco was consummated and the flowering of Teotihuacan takes place. Throughout this period there is a process of evolution acting from egalitarian agricultural societies towards more stratified ones that will conclude with the formation of the Teotihuacan national State.

just finished this it is b. centrifugal force

food chain i would say only because there is competition on getting food and survival