Answer:
D). the development of transportation and communication systems.
Explanation:
'Industrialization' in the United States was the product of several factors including a higher rate of immigration, decreased farm product prices, advancements in technology, development of transportation, as well as, communication systems, etc. The enhanced transportation through railroads and steamships along with expanded communication through telegraphs promoted the rapid growth of industries in the city. It further attracted the laborers to move to urban areas which increased the workforce significantly. Thus, option D is the correct answer.
