Question

why did factory owners and management often use force against striking workers?
they wanted to protect their families in case of worker uprisings.
they wanted to show that they were tough enough to run dangerous factories.
they hoped the use of force would keep the government from getting involved.
they hoped the use of force would keep workers from joining unions in the future.

Explanation:

Factory owners and management used force against striking workers to discourage union - membership. Unions could demand better wages, working conditions etc., which factory owners opposed. Using force was a way to intimidate workers and prevent them from joining unions in the future.

Answer:

They hoped the use of force would keep workers from joining unions in the future.