Which Precaution Is Most Important to Teach an Older Patient

Which precaution is most important to teach an older patient who is prescribed atazanavir (Reyataz) ?

A) "Be sure to take this drug at least 1 hour before or 4 hours after taking an antacid."
B) "Weigh yourself daily and notify your prescriber if you gain more than 2 lb in 1 week."
C) "Check your pulse for a full minute daily and notify your prescriber if it becomes irregular or slow."
D) "Check your calves daily for swelling or redness.If these symptoms appear,go to the emergency department immediately."