The correct answer is D.
The Industrial Revolution was the process of transition from craftmanship production methods to mass production systems and it led to the proliferation of factories. It ocurred in Europe and in the US at the end of the 18th century and during the 19th century.
Industrial sectors became the main source of labor demand in the economies. The new massive production systems required unskilled or semiskilled labor as the processes were divided in steps, and each of the steps comprised sime operations that any person could easily learn and perform efficiently.
