Question

what was an important labor reform during the progressive era?
securing workers compensation
reforming the tax system
limiting the workday to eight hours
forming the first unions

Explanation:

During the Progressive Era (late 19th - early 20th century), labor reforms were focused on workers' rights. Workers' compensation laws were an important part of this. They provided financial support to workers injured on the job. Reforming the tax system was more of a fiscal policy change (not directly labor - related). The eight - hour workday was a goal long before the Progressive Era (e.g., the 1886 Haymarket affair was related to the eight - hour day movement, but significant eight - hour laws for certain groups like government workers were earlier in some cases). The first unions (like the Knights of Labor in the 1860s) were formed before the Progressive Era.

Answer:

securing workers' compensation