Final answer:
William Jennings Bryan was not a radical labor leader, unlike the other individuals listed. He was known for his political career and involvement in the Populist movement rather than labor leadership.
Step-by-step explanation:
The student asked which of the following individuals were not radical labor leaders: Eugene Debs, William Jennings Bryan, "Big Bill" Haywood, and Daniel De Leon. Among the options given, William Jennings Bryan is the correct answer as he was not a radical labor leader. Bryan was more known for his political career, especially his three unsuccessful presidential campaigns and his work in the Populist movement, rather than as a labor leader.
Eugene Debs was indeed a radical labor leader, forming the American Railway Union and becoming a significant figure in the socialist movement in America. Similarly, "Big Bill" Haywood was a leader of the Industrial Workers of the World, and Daniel De Leon was a leader within the Socialist Labor Party, making them both key figures in the radical labor movement.