Answer:
The most significant factor of the Industrial Revolution that led to the development of the modern city was C. An increase of urbanization.
During the Industrial Revolution, there was a massive shift of people from rural areas to urban centers in search of employment opportunities in factories and industries. This rapid influx of people into cities resulted in the growth of urban areas and the development of modern cities.
Urbanization brought about significant changes in various aspects of city life, including the physical layout of cities, infrastructure development, social structure, and cultural dynamics. It led to the construction of factories, mills, and industrial complexes within urban areas, resulting in the concentration of economic activities and the transformation of cities into industrial hubs.
The increase of urbanization also played a crucial role in shaping transportation systems, as cities needed efficient modes of transportation to connect various parts of the urban area and transport goods and people to and from factories. This ties into option A, changes in transportation, as urbanization necessitated the development of transportation networks such as roads, railways, and later, public transportation systems.
While the spread of factories, changes in transportation, and housing developments were all significant factors during the Industrial Revolution, the increase of urbanization stands out as the most influential factor that shaped the development of modern cities.