**Core Concept**
Angiotensin II receptor antagonists (also known as angiotensin receptor blockers or ARBs) are a class of medications that block the action of angiotensin II at its receptor, preventing vasoconstriction and thereby reducing blood pressure. This mechanism is distinct from ACE inhibitors, which break down angiotensin II into a less active peptide.

**Why the Correct Answer is Right**
Losartan is an angiotensin II receptor antagonist that selectively binds to the AT1 receptor subtype, preventing angiotensin II from exerting its vasoconstrictive effects. By blocking the AT1 receptor, losartan reduces blood pressure and decreases the workload on the heart. This action is particularly beneficial for patients with hypertension, heart failure, and diabetic nephropathy.

**Why Each Wrong Option is Incorrect**
**Option A:** Perindopril is an angiotensin-converting enzyme (ACE) inhibitor, which works by breaking down angiotensin I into angiotensin (1-7) peptide, rather than blocking the angiotensin II receptor.
**Option B:** Enalapril is also an ACE inhibitor, similar to perindopril, and does not act by blocking the angiotensin II receptor.
**Option C:** Benazepril is another ACE inhibitor, which inhibits the conversion of angiotensin I to angiotensin II, rather than blocking the angiotensin II receptor.

**Clinical Pearl / High-Yield Fact**
It is essential to note that ARBs like losartan are often used as an alternative to ACE inhibitors in patients who experience cough or angioedema while on ACE inhibitors. Additionally, ARBs can be used in combination with other antihypertensive agents to achieve optimal blood pressure control.

✓ Correct Answer: D. Losartan