Kidney stones (renal calculi) are caused by:

Correct Answer: B

Rationale: Kidney stones form from mineral/salt precipitation not infection, dehydration (risk factor), or BP alone. This specifies etiology, critical for prevention, contrasting with secondary factors.

Correct Answer: B

Rationale: Juxtaglomerular cells in afferent arterioles secrete renin not macula densa (senses Na+), efferent arterioles, or lacis cells (support). This pinpoints renin source, critical for RAAS, contrasting with other JGA parts.

Correct Answer: B

Rationale: JGA (vascular pole, JG cells in afferent arterioles, macula densa) excludes intra-glomerular mesangial cells not part of JGA. This corrects JGA scope, critical for RAAS, contrasting with glomerular cells.

Correct Answer: D

Rationale: Medullipin I isn't from peritubular endothelium (medullary interstitial cells) other associations (PCT/brush, bladder/transitional, DCT/macula) are correct. This corrects hormone source, key for BP regulation, contrasting with true pairs.

Correct Answer: C

Rationale: Columns of Bertin are cortical tissue between pyramids not rays (cortex-medulla), interlobular (vague), or sinus (cavity). This repeats Q4, key for anatomy, contrasting with other terms.