Which labor leader is best known for promoting the 8-hour workday and advocating for labor reforms on the Fourth of July?

Ira Steward is best known for his advocacy of the eight-hour workday and for promoting labor reforms specifically highlighted during celebratory occasions such as the Fourth of July. Steward's efforts in the labor movement focused on improving working conditions, and he played a significant role in organizing labor strikes and rallies to push for the eight-hour workday, arguing that it was essential for workers' rights and quality of life. His activities connected the labor movement with broader social and political issues, effectively using patriotic celebrations to garner support for labor reforms. This context makes him a pivotal figure in labor history concerning the demand for an eight-hour workday.

The other choices represent important labor leaders as well, but they did not specifically champion the eight-hour workday in the same manner or are not particularly known for advocating on the Fourth of July in that capacity.