By the beginning of the twentieth century, the united states economy revolved around
a. agriculture.
b. education.
c. trucking.
d. factories.

I think it is D.Factories

Explanation

Around this time the economy in the US became very industrial because of the fall of agriculture since a lot of farmers moved north to work in factories

if i am correct the answer is going to be a) the federal program of reconstruction ended.

the viking voyages took place during the middle ages, which was about this time. 500 to 1350. the viking voyages took place during the middle ages, which was about this time.