6. (SSEMI2F) If consumers' incomes rise, the demand curve will shift a. To the left
b. To the right

Could you give me some more details so i can you?

One of the things that allowed native americans in mexico to settle cities larger than those in areas to the north was "b. the development of cities that were built by an earlier civilizations," since mexico had been the home of some of the world's most advanced civilizations before the columbian invasion