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.

the reason the two sea urchins don't compete with each other for food, resources, etc. is because the urchins have adapted to the environment but they have also adapted to each other. this is most likely because the genes of the sea urchins.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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