There had to be unanimity but that made it really hard for the league to do anything and the league suffered badly from the absence of major powers. Germany, Japan and Italy left and there was a lack of U.S participation
The answer is B) Inca. Extensive road network across plains, deserts and mountains reaching all corners of the empire was one of the notable features of the Inca empire like terraced farming, canals, crop rotation and irrigation as agricultural innovations. It allowed smooth military operations, trading, and the use of runners or chasquis.
