Which present-day state was part of the Louisiana Purchase?

A) Oklahoma

Explanation:

We can rule out Florida and Georgia because those states were east of the Louisiana Purchase area. This area covered much of the present-day US, and this area was a big chunk of the middle section. California wasn't part of the Louisiana Purchase. This state was part of the aftermath of the Mexican-American War, due to the Treaty of Guadalupe Hidalgo. So we can rule out California as well. The only thing left is Oklahoma, which is in the region described in the start of this paragraph.