D) The Appalachian Mountains blocked English movement westward
Explanation:
Once the English set foot in the New World they quickly started to settle in and create lot of settlements. There were lot of expeditions organized with the purpose to better know the new lands, to see if there's more of it that can be used, is there natural resources, other people etc. The explorations though were initially limited to the east coast and the eastern part of the Appalachian Mountains. The reason for this was that the Appalachians were a mountain range that was acting like a natural barrier, having roughly northeast-southwest direction, it was setting apart the eastern coast from the interior of the continent. The high mountain range was too tough and too high for crossing in that period, so explorations west of it were largely avoided.
