Select the reason cities tend to develop at the fall line on rivers

1. Access to water transportation: The fall line marks the point where river navigation becomes difficult due to rapids or waterfalls. Cities located at the fall line can take advantage of this natural barrier to control and tax river traffic, as well as provide services like port facilities for boats to bypass these obstacles.

2. Access to water power: The presence of waterfalls or rapids at the fall line provides a source of hydropower that could be harnessed for industrial or agricultural purposes. This can attract businesses and industries to establish themselves in these cities.

3. Natural resources: The presence of fertile land, forests, or mineral deposits near the fall line can attract settlers and lead to the development of cities as people come to exploit these resources.

4. Defense: The fall line can serve as a natural defensive barrier against enemies or invaders, making it an attractive location for settlement and the development of fortified cities.

5. Trade and commerce: The location of cities at the fall line allows them to serve as centers of trade and commerce, as goods transported along the river must pass through these points. This can lead to the growth of markets, fairs, and other economic activities in these cities.