CREATE TABLE table_33639 ("Player" TEXT, "Nationality" TEXT, "Position" TEXT, "From" TEXT, "School/Country" TEXT)

What school did the guard who began playing in 1991 come from?
SELECT "School/Country" FROM table_33639 WHERE "Position" = 'guard' AND "From" = '1991'
SELECT "School/Country" FROM "table_33639" WHERE "From" = '1991' AND "Position" = 'guard'