The large connected urban area from boston to washington, dc, is often referred to as a(n) a. metropolis b. megalopolis c. suburb d. urban zone

The correct answer is option B, Megalopolis

When two or more large metropolitan cities are so nearing in their geographical boundaries that they merge to form a large urban area known as Megalopolis. The merging cities have high end integrated infrastructure and possess a high density population. As per Gottmann, Megalopolis can  be referred to as a large functional urban region. The region between Boston and Washington DC include several other cities like New York, Providence, Hartford, New Haven, Philadelphia and Baltimore is the most prominent Megalopolis region of Washington DC.