**Core Concept**
Renal artery stenosis (RAS) refers to the narrowing of the renal arteries, which supply blood to the kidneys. This condition can lead to various clinical manifestations due to the reduced blood flow to the kidneys. The features of RAS include hypertension, asymmetrical kidney size, and the presence of atherosclerotic plaques.

**Why the Correct Answer is Right**
Option A, "Hypertension responds well to drugs," is incorrect because patients with RAS often have resistant hypertension that does not respond well to conventional antihypertensive medications. This is due to the fact that the kidneys are underperfused, leading to activation of the renin-angiotensin-aldosterone system (RAAS), which in turn causes vasoconstriction and increased blood pressure. The use of ACE inhibitors or ARBs can actually worsen hypertension in patients with RAS by further reducing glomerular filtration rate (GFR) and increasing angiotensin II levels.

**Why Each Wrong Option is Incorrect**
**Option B:** Asymmetrical kidney size is a feature of RAS, often due to the presence of a stenotic artery on one side, which leads to atrophy of the affected kidney. This is a common finding in patients with RAS.
**Option C:** Atherosclerotic plaques are indeed common in patients with RAS, particularly in the elderly population. The presence of plaques is often associated with atherosclerotic disease in other vascular beds.
**Option D:** Serum creatinine may increase with ACE inhibitors in patients with RAS due to the reduction in GFR. This is a known adverse effect of ACE inhibitors in patients with bilateral RAS or unilateral RAS with a solitary functioning kidney.

**Clinical Pearl / High-Yield Fact**
A key clinical pearl to remember is that patients with RAS often have a "renal-brachial index" of <0.9, which is calculated by dividing the diameter of the right renal artery by the diameter of the right brachial artery. This index can help diagnose RAS in patients with suspected renovascular hypertension.

**✓ Correct Answer:** A. Hypertension responds well to drugs.