Which of the Following Statements About Creating Constraints Is Incorrect

Which of the following statements about creating constraints is incorrect?

A) If you do not provide a name for a constraint, the Oracle11g server will issue an error message.
B) There are two approaches for creating constraints: at the column level or the table level.
C) One industry convention is to use the format tablename_columnname_constraint type for the constraint name.
D) none of the above