What Is the Most Important Precaution to Teach a Patient

What is the most important precaution to teach a patient who has a continuous infusion of treprostinil to manage pulmonary artery hypertension?

A) "Avoid crowds and people who are ill."
B) "Use at least two reliable forms of birth control."
C) "Go to the nearest emergency room if the line clogs."
D) "Report a headache lasting 24 hours to your prescriber immediately."