What role did radiocarbon dating have in uncovering clues of why the Maya civilization collapsed?

Two of these describe “federalism." (choose two answers) select one or more: a. the national government absolutely controls all state governments. b. power is shared by the national and state governments. c. state governments exercise absolute power over the national government. d. it is a compromise meant to eliminate the disadvantages of a “unitary” and a “confederate” system.