The pronephros is developed from intermediate mesoderm in the:

Correct Answer: A

Rationale: Pronephros forms in the cervical region of intermediate mesoderm not thoracic, lumbar, sacral, or combined. This transient structure (week 4) regresses in humans, giving way to mesonephros. Its cranial location reflects early embryonic patterning, key for understanding nephric succession, contrasting with caudal regions.

Correct Answer: D

Rationale: Bladder forms from vesicourethral canal (body), allantois (apex), and mesonephric ducts (trigone) all apply. 'All' captures full origin, key for anatomy, contrasting with partial selections.

Correct Answer: B

Rationale: Kidneys maintain acid-base balance by excreting H and reabsorbing HCO₃⁻ e.g., PCT reclaims HCO₃⁻, distal tubule secretes H . Excreting both loses buffer acidosis risk. Reabsorbing H /excreting HCO₃⁻ reverses alkalosis. Reabsorbing both retains acid imbalanced. H excretion/HCO₃⁻ retention distinguishes it, key to pH regulation, unlike dual loss or retention.

Correct Answer: D

Rationale: The trigone is the bladder's three openings two ureters, one urethra (e.g., triangular region). Detrusor is muscle not openings. Rugae are folds not specific. Cortex is kidney not bladder. Trigone's anatomical term distinguishes it, key to bladder structure, unlike muscle or unrelated areas.

Correct Answer: C

Rationale: Filtration based on blood pressure occurs at the glomerulus hydrostatic pressure (~55 mmHg) drives GFR (e.g., renal corpuscle). Collecting duct reabsorbs not filters. Distal tubule adjusts post-filtration. Loop concentrates not pressure-driven. Glomerulus's pressure filtration distinguishes it, key to urine initiation, unlike tubular roles.