Which of the following is commonly used to treat hypertension?

Calcium channel blockers are commonly used to treat hypertension because they work by inhibiting the entry of calcium into the smooth muscle cells of the heart and blood vessels. This leads to relaxation of the vascular smooth muscle, resulting in vasodilation and subsequently lowering blood pressure. These medications help to reduce the workload on the heart and decrease the rate at which the heart beats, making them effective agents in managing high blood pressure.

The other options do not serve this purpose: antacids are primarily used to neutralize stomach acid, antihistamines are used to treat allergic reactions and conditions such as colds, and vitamins don't have a direct role in lowering blood pressure. Thus, calcium channel blockers are specifically targeted for hypertension treatment, making them the correct choice.