What may have strengthened Iroquois leaders' resolve not to ally with Britain?

Because great britian lost the battle in fort Niagara and lake George

Explanation:

The Iroquois decided not to ally themselves, probably because of the defeat that Great Britain  suffered in Fort Niagara and Lake George.

The Iroquois were a Native American group that lived in the Great Lakes region where today is the state of New York in the United States. Five nations - caugas, mohawks, oneidas, onondagas and sínecas - originally constituted the Iroquesa Confederation.

Explanation:

(happy to help)

the answer would be c

the monroe doctrine is the best known u.s. policy toward the western hemisphere. buried in a routine annual message delivered to congress by president james monroe in december 1823, the doctrine warns european nations that the united states would not tolerate further colonization or puppet monarchs.