Final answer:
Labor unions in the U.S. developed in response to harsh factory conditions, including long work hours, low wages, and dangerous working environments, leading to worker injuries.
Step-by-step explanation:
The creation of labor unions in the U.S. was predominantly a response to the challenging working conditions faced by factory workers during the Industrial Revolution. Conditions such as long work hours, dangerous machinery leading to injuries, extremely low wages, and poor overall working conditions were prevalent. These factors, combined with a surplus of labor that kept wages low and replaced injured or dissatisfied workers, left employees with little bargaining power or job security.
As a result, the establishment of labor unions was a means for workers to collectively advocate for better treatment, safer work environments, fair wages, and reasonable work hours. The unions sought to balance the power dynamics between factory owners and workers, fighting for legal recognition and the right to collective bargaining for the improvement of all workers' conditions.
Thus, the correct answer to the question is B: Long work hours and worker injuries on the job led to the development of labor unions in U.S. factories, along with other severe working conditions.