Q1 Single choice Flag Which statement is correct about informational constraints? A An informational constraint can be used by the SQL compiler to improve the access to data and query performance. B The database manager uses an informational constraint to enforce the uniqueness of the key during changes to the columns of the unique constraint. C An informational constraint is a column or combination of columns that has the same properties as a unique constraint. D An informational constraint specifies that every row that is inserted or updated in the table must conform tothe definition of the table. Correct answer