In Colonist-Indian Relations, What Was Known as the "Middle Ground

In colonist-Indian relations, what was known as the "middle ground"?

A) Colonists' and Indians' trading with each other and operating as equals
B) Quakers' living alongside Indians in settlements where no violence was tolerated
C) Regions where Indians and Europeans shared the best land for growing crops
D) The first joint feast between Europeans and Indians
E) Land that colonists agreed not to encroach upon