user: Question: What school did the Guard who began playing in 1991 come from?
Columns: ['Player', 'Nationality', 'Position', 'From', 'School/Country']
Types: ['text', 'text', 'text', 'text', 'text']
Sample row: [', Robert Sacre', 'Canada', 'Center', '2012', 'Gonzaga']
SQL:

assistant: SELECT "School/Country" FROM "Table" WHERE "Position" = 'Guard' AND "From" = '1991';