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 on a fairly equal basis.
B) The Quakers living in settlements alongside Indians 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 (later known as Thanksgiving) .
E) Land that colonists agreed not to encroach upon.