The American system of manufacturing was developed in the early 1800s. There is general agreement that the War Department was the driving force behind the development. Around this time, the Department was aiming to reduce costs on the manufacture, maintenance and repair of the armory, and so it encouraged innovators make machine parts interchangeable. This meant that, in the event of a mechanical problem, a single part of the machine could be replaced easily rather than having to be sent back to the manufacturer for repair. Interchangeability was achieved through the use of templates and machine tools to make parts that were identical in size and shape. The work of molding the templates and cutting out the pieces needed to be done by trained and experienced factory relatively simple work under this regimen, and it could now be easily undertaken at a separate location by unskilled laborers. This division of labor ultimately allowed workers were considerably less than those of the semi-skilled workers who were capable of operating the machines. Direction: an introductory sentence for a brief summary is provided below passage 1 to 4. Complete the summary by selecting the Two answers choices that express the most important ideas in each passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. Driven by the War Department, a more efficient system of manufacturing was developed in America in the early 19 th century.