The correct answer is B) the industrial workforce from minority unionized to majority unionized.
The changes that took place in the first two decades of the 20th century were that the industrial workforce from minority unionized to majority unionized.
What happened during this time is that the workplace lacked many considerations for the workers. It had only major advantages for employers and owners. So in order to balance the situation and improve the working conditions of the workers, the labor movement in America grew in dimension and influence during the first two decades of the 20th century. Labor wanted to protect the interests of the labor force. The plea was for better wages, better working conditions, and reasonable hours at work.