C) Union membership increased because workers wanted protection from the policies of business owners.
During the late 1800s and early 1900s, industrial growth often resulted in poor working conditions, long hours, and low wages for many workers. This led to increased interest in labor unions as workers sought to advocate for their rights and improve their conditions. Unions provided a way for workers to collectively bargain and push back against the policies and practices of business owners, leading to an increase in membership.