I think its B. Fertile Land because the Gangas and Indus river are very helpful with making the land more fertile. When land is more fertile it is easier to farm, so people go there to start farming and then they can feed themselves and their family.
El territorio continental de los Estados Unidos limita al este con el Océano Atlántico, al sureste con el Golfo de México y al oeste con el Océano Pacífico.