Tiffany recently discovered that the reject rate for her department has exceeded the standard for performance in this area. What should Tiffany do to exercise effective control?

a$.$ She should order more training for her workforce.

b$.$ She should contact the maintenance department and have them come fix her machinery.

c$.$ She should suspend the poorer workers in her department.

d$.$ She should investigate and discover the cause of the problem.

e$.$ None of these