In a certain city there is a river running through the middle of the city. There are four islands and eleven bridges as shown in the figure below.
Suppose that there is a crossing charge of $1.00 every time one crosses a bridge. A tourist wants to start on the South Bank, stroll across each of the bridges at least once, and return to her hotel on the South Bank at the end of the trip. What is the cheapest possible cost of such a trip?
◦ $14
◦ $12
◦ $11
◦ $13
◦ none of these