A.SELECT UNIQUE dept FROM staff
B.SELECT DISTINCT dept FROM staff
C.SELECT (dept) UNIQUE FROM staff
D.SELECT (dept) DISTINCT FROM staff

A.A table referenced in the FROM clause has no indexed column.
B.The table referenced in the FROM clause has more than 200 columns.
C.Two or more tables in the FROM clause have identical column names.
D.The FROM clause contains two or more tables in the SELECT statement.