Interchangeable parts were invented a) about the same times the wagons were invented. b) about the same time robots were invented. c) after robots were invented. d) before the invention of the assembly line.

a) about the same times the wagons were invented.

Explanation:

Interchangeable parts are the identical parts which are produced such as that if a vehicle for the sole aim of mass production. They are also known as spare parts and are used in assembling other goods. An example of goods where interchangeable parts are used include rail roads, cars , ships etc.

The earliest and commonest means of transportation in America were the wagons which were used to transport goods and services. The interchangeable parts were produced about the same times the wagons were invented.

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