Select a water-soluble vitamin:

Correct Answer: D

Rationale: The correct answer is D: Vitamin B1. This is a water-soluble vitamin, also known as thiamine. Water-soluble vitamins dissolve in water and are not stored in the body, so they need to be consumed regularly. Vitamin A (choice A), Vitamin E (choice B), and Vitamin D (choice C) are fat-soluble vitamins, meaning they are stored in the body's fat tissues and liver, not excreted in urine like water-soluble vitamins. Therefore, they are not water-soluble vitamins. Vitamin B1 (choice D) is crucial for energy metabolism and nerve function, making it a water-soluble vitamin that needs to be replenished regularly through diet.

Correct Answer: D

Rationale: The correct answer is D: Probucol (Lorelco). Probucol decreases blood levels of HDL by inhibiting the enzyme that helps in the production of HDL. Lovastatin (A) works by lowering LDL levels, Nicotinic acid (B) increases HDL levels, and Gemfibrozil (C) works mainly on triglycerides and raises HDL levels. Probucol (D) is specifically known for lowering HDL levels.

Correct Answer: C

Rationale: The correct answer is C: Hypophosphatemia. Etidronate is a bisphosphonate used to treat Paget's disease and osteoporosis by inhibiting bone resorption. Hypophosphatemia is a condition characterized by low phosphate levels in the blood, and etidronate is not indicated for this. Hypercalcemia is not an indication for etidronate as it can further decrease calcium levels.

Correct Answer: B

Rationale: The correct answer is B: Furosemide (Lasix). Furosemide is a loop diuretic that specifically targets the sodium/potassium/chloride cotransporter in the thick ascending loop of Henle. By blocking this transporter, furosemide inhibits sodium reabsorption, leading to increased diuresis. Acetazolamide works in the proximal tubule, hydrochlorothiazide acts on the distal convoluted tubule, and amiloride targets the epithelial sodium channels in the collecting duct. Therefore, they are not the correct choices for blocking the sodium/potassium/chloride cotransporter in the thick ascending loop of Henle.

Correct Answer: B

Rationale: The correct answer is B: Gentamycin. Aminoglycosides are a class of antibiotics that inhibit bacterial protein synthesis. Gentamycin falls under this class due to its mechanism of action. Erythromycin (A) is a macrolide antibiotic, Vancomycin (C) is a glycopeptide antibiotic, and Polymyxin (D) is a polypeptide antibiotic. These antibiotics do not belong to the aminoglycosides class, making them incorrect choices.