Beta blockers have which primary effect on the body?

Beta blockers primarily work by decreasing heart rate and helping to dilate arteries. These medications block the effects of adrenaline on the beta-adrenergic receptors in the heart and blood vessels. As a result, the heart beats more slowly and with less force, leading to reduced blood pressure. This can benefit individuals with conditions such as hypertension or certain heart disorders by lowering the workload on the heart and improving blood flow.

In this context, the increase in heart rate associated with physical activity or stress is countered by the action of beta blockers. The dilation of arteries further supports better circulation, which can enhance overall cardiovascular function. Therefore, the primary effect of beta blockers aligns with this description, making it the correct answer.