Which of the following drugs is an alpha-blocker?

Correct option is D

Prazosin is an alpha-adrenergic blocker used to treat hypertension and PTSD. It causes vasodilation by blocking alpha-1 receptors in blood vessels.
Explanation of options: (a) ✘ Propranolol is a beta-blocker. (b) ✘ Nifedipine is a calcium channel blocker. (c) ✘ Verapamil is also a calcium channel blocker. (d) ✔ Prazosin is the only alpha-blocker in the list.