Read the passage from The American Plague. All along the way Jefferson chafed at the jump in prices brought about by "harpies who prey upon travelers" returning to Philadelphia. Inns on the route had upped their rates; ferrymen were charging extra to transport people and carriages across rivers. In the end, Jefferson estimated that it cost him nearly eighty dollars just to get to Germantown.

What was the cause of the jump in prices?

the cost of ferry boats
the yellow fever outbreak
the number of people traveling
the amount of heat, rain, and dust