Correct Answer: C
Beta-blockers are commonly prescribed medications for arrhythmias (abnormal heart rhythms), as well as for conditions like hypertension and certain forms of heart failure. The NASM CPT7 Study Guide explains that cardiovascular disease includes "heart rate problems, and arrhythmias", and medications such as beta-blockers help regulate heart rhythm by blocking the effects of adrenaline on the heart's beta receptors. This results in a slower, more controlled heart rate and reduced workload on the heart.
In exercise settings, CPTs must be aware that beta-blockers lower both resting and exercise heart rates, which makes heart rate-based training zones less reliable; perceived exertion (RPE) or talk tests are recommended instead for intensity monitoring.
Other listed options-nitrates (for angina), diuretics (for fluid retention in hypertension/heart failure), and bronchodilators (for respiratory conditions)-do not serve as primary rhythm-control agents for arrhythmias.
Thus, beta-blockers are the most accurate answer for this question.