Examine the following statement that is used to modify the primary key constraint on the SALES table： SQL> ALTER TABLE SALES MODIFY CONSTRAINT pk DISABLE VALIDATE； Which three statements aretrue regarding the above command（）

• A、The constraint remains valid.
• B、The index on the constraint is dropped.
• C、It allows the loading of data into the table using SQL *Loader.
• D、New data conforms to the constraint， but existing data is not checked.
• E、It allows the data manipulation on the table using INSERT/UPDATE/DELETE SQL statements.