Which command will provide additional information about the error?

You try to add a foreign key to the InnoDB table employees:
Mysq1> ALTER TABLE employees ADD FOREIGN KEY (Department_ID) REFERENCES
departments (Department_ID);
ERROR 1215 (HY000): cannot add foreign key constraint
Which command will provide additional information about the error?

A.
SHOW ERRORS

B.
Error 1215

C.
SHOW ENGINE INNODB STATUS

D.
SELECT FROM information_schema.INNODB_SYS_FOREIGN

Explanation:
Reference:
http://zeering.com/LoadAnswers.aspx?q=Foreign%20Key%20constraint (see update)