Which early river valley civilizations are marked with the letters a and b on this map?

i think the answer is c, rivers.

explanation:

sometimes, borders fall along natural boundaries like rivers or mountain ranges. for example, the boundary between france and spain follows the crest of the pyrenees mountains. for part of its length, the boundary between the united states and mexico follows a river called the rio grande. the borders of four countries divide africa’s lake chad: niger, chad, cameroon, and nigeria.

ilikeair12 history; do you think the american dream is still attainable? kristinalovestae history; which of the following describes a technological accomplishment of the 1920s a. the completion of the panama canal b. the solo non-stop transatlantic

hope this : d