user: Question: What is the nationality of the round 4 draft selection who played college ball at Oklahoma?
Columns: ['Round', 'Pick', 'Player', 'Nationality', 'College']
Types: ['real', 'real', 'text', 'text', 'text']
Sample row: [1.0, 22.0, 'Reggie Lewis', 'United States', 'Northeastern']
SQL:

assistant: SELECT "Nationality" FROM "Table" WHERE "Round" = 4.0 AND "College" = 'Oklahoma';