The major cause of morbidity in schistosomiasis is:

Correct Answer: B

Rationale: Schistosomiasis morbidity stems from eggs causing inflammation/fibrosis, not worms, miracidia (free-living), or 'schistooulium' (typo). This identifies pathogenic stage, key for complications, contrasting with adult worm effects.

Correct Answer: A

Rationale: Praziquantel disrupts schistosome membranes via Ca2+ influx not Mg2+, Na+, or K+. This specifies antiparasitic action, key for schistosomiasis treatment, contrasting with other ions.

Correct Answer: C

Rationale: Triamterene (K+-sparing) can reduce free water clearance, causing antidiuresis not loop (bumetanide), thiazide (chlorthalidone), or osmotic (urea). This distinguishes paradoxical effect, key for electrolyte therapy, contrasting with typical diuresis.

Correct Answer: D

Rationale: JG cells secrete renin and are in afferent arterioles not efferent, DCT (macula densa), or glomerulus. This specifies renin source, key for RAAS, contrasting with mislocations.

Correct Answer: D

Rationale: Urethra, ureter, and bladder are urinary; prostate is reproductive not urinary. This excludes non-urinary structures, key for system scope, contrasting with excretory components.