During the Seventeenth Century, When European Fur Traders Arrived, the Iroquois

During the seventeenth century, when European fur traders arrived, the Iroquois changed from a peace-loving tribe to fierce enemies of their neighbors, the Hurons. This suggests that

A) there are consistent cultural norms driving the expression of aggression.
B) tribal inbreeding selected for aggressive behaviors.
C) economic and social competition can elicit aggression.
D) aggression is affected by innate propensities and learned inhibitory responses.