Final answer:
A nurse should monitor for postural hypotension as an adverse reaction to propranolol, a β-blocker medication prescribed for conditions such as hypertension. (Option c)
Step-by-step explanation:
The correct answer to the question posed by the student is C. Postural hypotension. Propranolol is a medication that belongs to a class of drugs known as β-blockers, which are often prescribed to treat cardiovascular diseases such as hypertension.
These drugs work by blocking β-receptors associated with vasoconstriction and cardioacceleration. Since propranolol nonspecifically blocks β-receptors, it can lead to vascular dilation and reduced heart rate. An adverse reaction to look out for while taking β-blockers like propranolol is postural hypotension, which signifies a drop in blood pressure when standing up from a sitting or lying position, possibly causing dizziness or fainting.