People believed that the dangerous and horrible working conditions they were subjected to would be fixed by competition and interaction in the marketplace.
People in the first half of the 20th century were strong believers that the market would always work to ensure the efficient distribution of resources.
They therefore thought that the market would correct the abuses in the labor market, and so didn't pressure the government enough to make changes.
In conclusion, option D is correct.
Find out more on labor practices in the early 20th century at https://brainly.com/question/1995704.