Answer:
A.It provided the United States access to the Mississippi River.
Step-by-step explanation:
The Pinckney's Treaty of October 27, 1795 was an important treaty that established trade and diplomacy relations between Spain and U. S. It was important to the expansion of the United States because it provided the United States access to the Mississippi River.
The treaty secured American ships the freedom to take routes through the Mississippi River without any export duties and free transport was also provided upto the ports of New Orleans.