Answer: A) the Northwest Passage
Most of the Europeans who explored the Upper Mississippi River region were focused on finding the Northwest Passage.
Step-by-step explanation:
The Northwest Passage is a sea route to the Pacific Ocean and Atlantic Ocean which is easier and shorter route.
The most of Europeans sailors were determined to discover that route because it helped them to the faster resource transportation.
In past it was believed impossible to cross the Northwest Passage because of the ice block disturbing the route.