What Is the Most Important Precaution to Teach a Patient

What is the most important precaution to teach a patient prescribed brimonidine (Alphagan P) eye drops for glaucoma?

A) Increase the room lighting when reading or doing close work.
B) Stop using the drug and notify your prescriber if crusts form on the eye lid.
C) Do not take this drug beyond the period your doctor prescribed even if some drug remains in the bottle.
D) Avoid wearing prescription reading glasses or sun glasses while you are taking this drug.