Answer:
Option: C. the Falls of Ohio
Explanation:
The falls of Ohio was an obstacle for steamboats travelling down the Ohio River in the 19th century because of its geographic features which included a series of rocky rapids. The falls of Ohio at Louisville formed the obstacle to navigation on the river because of limestone shoals that created rapids. Smaller boats were able to navigate the falls in high water, but larger steamboats always ran the risk of damage.
