Which geographic feature contributed most to the settlement of colonies along the atlantic coast?

The Appalachian Mountains most contributed to the settle of the colonies along the Atlantic coast. As the settlers were just attempting to establish themselves in the harsh terrain of unsettled environments, they avoided the additional difficulties of spreading out further and over a mountain range. The coastal areas would have been able to provide initial raw materials to start colonization without risking more by attempting to overtake the mountain range.

I'd say the answer is a, but i could be wrong