Said city is the capital of Pennsylvania where all the commerce is carried on . . . On two sides the city has navigable waters . . . Many large and small merchant-vessels are built there near the water. The trade of the city and country to other countries and colonies increases perceptibly from year to year; it consists in fruit, flour, corn, tobacco, honey, skins, various kinds of . . . furs, flax, and particularly a great deal of flax-seed or linseed, also fine cut lumber, horses, and all kinds of tame and wild animals. In return the incoming vessels bring all sorts of goods, such as . . . spices, sugar, tea, coffee, rice, rum … Based on this passage, which statement about the Middle Colonies is most accurate?

a
the geography isolated the region from the outside world
b
settlements were self-sufficient
c
the geography made it difficult to build large settlements
d
settlements were built around port cities