Before New Orleans Developed into a Major Tourist Destination,what Was

Before New Orleans developed into a major tourist destination,what was the main factor that led to it being a key center for trade?

A) It was a free port (no tariffs) for the English,French and Spanish.
B) Its location near the mouth of the Mississippi river
C) The beautification and gentrification efforts led by Andrew Jackson and Sir Edward Pakenham in 1815.
D) New Orleans provided a ready supply of sailors to visiting vessels in the 19th century.