What Encouraged the Building of Factories in Coastal Towns Such

What encouraged the building of factories in coastal towns such as New Bedford and even large inland cities such as Chicago by the 1840s?

A) Such places generally had cheaper labor (usually consisting of African-Americans) than existed in the earlier, highly unionized factory towns such as Lowell and Pawtucket.
B) Under Henry Clay's American System, federal and state governments subsidized factories in those locations.
C) Steam power meant factories no longer had to be near waterfalls and rapids to generate the power.
D) Factory owners were attracted by the highly skilled labor pool of German immigrants who settled in those areas.
E) The U.S. Supreme Court's decision in Gibbons v. Ogden removed obstacles to the placement of factories in densely populated areas.