The treaty of san lorenzo allowed americans living west of the appalachian mountains to
a.
build a military post in new orleans to protect american travelers
b.
have the right of deposit while using the port of new orleans to trade
c.
trade with american indians living in the louisiana territory
d.
live on spanish lands so long as they spoke spanish

B.  have the right of deposit while using the port of New Orleans to trade

Explanation:

The "Treaty of Friendship, Limits, and Navigation between the United States of America and the King of Spain” or Treaty of San Lorenzo was an agreement between Spain and the United States stablished in 1795. It fixed the boundariy of the U.S. and stablished comercial arrangements that were in favour to the U.S. These countries arranged free navigation of the Mississippi River through Spanish territory, it also permited U.S. citizens to deposit goods duty-free at New Orleans.

porter is writing economic history because he is focusing on the cost of developing vaccines.