Jefferson completed the lousisiana purchase even though

The correct answer to this open question is the following.

US President Thomas Jefferson completed the Louisiana purchase even though he thought that this decision was not specifically authorized by the United States Constitution. So he feared that this decision could be unconstitutional.

However, Jefferson opted to move on with the purchase that was concluded in 1803. President Jefferson had sent James Madison to Paris, France, to help Robert Livingstone, who was the US minister to France, to conclude the negotiations. France sold the Louisiana territory in $11,250,000. It represented about 820,000 square miles of territory.

this is a good question! i'll do some research and come back when i have the answer!