Which Precaution Is Most Important for the Nurse to Teach

Which precaution is most important for the nurse to teach a patient who is prescribed an antacid?

A) "Avoid using extra pepper on your food while taking this drug."
B) "If you become constipated, stop taking the antacid completely."
C) "Take this drug at least 2 hours before or after taking any other drug."
D) "Notify your prescriber if heartburn continues after you have taken the drug for 3 days."