The fourth answer is correct (D).
The development of the manufacturing environments generated a strong demand for workers, being the first great training fafor of the working class.
At that time there were no labor laws, so the men worked 6 to 7 days a week, with low wages, and hours that went beyond 12 hours a day. For an even smaller salary, women and children were subjected to the same tasks as the grown men. At the same time, the working conditions offered at the factories were precarious. Without proper facilities and no safety, the factories offered a risk of damage to the health and physical integrity of the workers.