The correct anwer is (D). The interchangeable parts were first used in the US by Eli Whitney who was its inventor. Whitney was an American inventor born in Massachusetts (1765). He used the interchangeable parts for the first time when assembling muskets for the government of the EE.UU., in this way it was possible for unskilled workers to produce large number of weapons quickly and at lower cost. Whitney's invention made also possible to repair and replace parts easily.
