Answer:
A. The opening up of new markets to good
Step-by-step explanation:
During the second industrial revolution, the advancement in the use iron and steel brought a significant change. The development of railroads helped in the cheap and better communication of goods. The increase in the products made in factories curbed the space for the requirement of skilled labor. The cities witnessed growth and there stood the emergence of national market. Railroads helped in the growth of middle class and in small businesses.