I think D, because it talks about prompting more people to migrate.
It was built to create a navigable water route from New York City to the Great Lakes.
Divergent boundaries move oceanic plates (plates found in the ocean) away from each other, making magma seep in to fill those cracks, thus spreading the sea floor.
The appropriate choice for the non-event is ...
... A. The costs of sewing machines began to increase.
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Interchangeable parts generally reduce costs and increase demand (and production).
