Answer:
C. Lack of regulation led to long hours, low pay, and dangerous
working conditions.
Step-by-step explanation:
The Industrial Revolution represented an enormous change in the working conditions of most of the working class. In fact, it is only after the Industrial Revolution that we talk of a "working class", since before, most people of low social status were peasants.
During the first decades of the Industrial Revolution, labor was mostly unregulated, and firms took advantage of this by exploiting their workers as much as possible, making them work very long hours, with little pay, and under dangerous or harsh conditions.
This prompted the birth of social movements and workers' unions, who demanded better working conditions, like better pay, a 8 hour daily shift, and vacation time. With time, in most countries in the world these demands became laws, which means that nowadays working conditions are much better.