The correct action is D) business owners.
According to Progressives, the group that should be responsible for employee injuries that occurred on the job were business owners.
As the name indicates, the Progressists belonged to the Progressive era of political and social reforms from 1890 to 1920. The movement was a kind of response to the many problems that industrialization brought to the United States such as unhealthy and risky working conditions, more than eight hours of work daily and low wages for the workers. So it is correct to say that according to Progressives, the group that should be responsible for employee injuries that occurred on the job were business owners.
The other options of the question were a) reformers, b) workers, and c) activists.