Answer:
Option C, decreased heart rate
Step-by-step explanation:
Digoxin is an anti-arrhythmic medication indicated for patients with heart failure (HF). By increasing the force of the myocardial contraction and decreasing electrical conduction through the two main nodes of the heart, cardiac output is increased, electrical conduction decreases, and the heart rate decreases, all of which help with decreasing the severity of HF.
So, if the nurse wants to look for evidence that the medication is effective, the nurse should monitor that the patient experiences a decrease in heart rate, option C.