The Nurse Has Completed Patient Teaching About the Administration of Salmeterol

The nurse has completed patient teaching about the administration of salmeterol (Serevent) using a metered-dose inhaler (MDI) . Which action by the patient indicates good understanding of the teaching?

A) The patient attaches a spacer before using the MDI.
B) The patient coughs vigorously after using the inhaler.
C) The patient floats the MDI in water to see if it is empty.
D) The patient activates the inhaler at the onset of expiration.