Loosening of teeth, gingivitis and hemorrhage occur in the deficiency of:

Correct Answer: D

Rationale: Step-by-step rationale for why Vitamin C (Choice D) is the correct answer: 1. Vitamin C is essential for collagen synthesis, which is crucial for maintaining the integrity of gum tissues. 2. Deficiency of Vitamin C leads to weakened collagen, causing symptoms like loosening of teeth, gingivitis, and hemorrhage. 3. Vitamin K (Choice A) is important for blood clotting, not directly related to gum health. 4. Vitamin B1 (Choice B) is essential for energy production, not directly linked to gum health. 5. Vitamin B6 (Choice C) is involved in various metabolic processes, but not specifically related to gum health. Summary: The correct answer is Vitamin C (Choice D) because it is directly linked to maintaining healthy gum tissues by supporting collagen synthesis. Choices A, B, and C are incorrect as they are not directly associated with the symptoms of loosening of teeth, gingivitis, and hemorrhage.

Correct Answer: D

Rationale: The correct route of administration for 1,25-dihydroxyvitamin D3 (calcitriol) is oral (Choice D). This is because calcitriol is a form of vitamin D that is typically taken orally for absorption in the intestine. When taken orally, it undergoes hepatic and renal hydroxylation to its active form. Subcutaneous (Choice A), intravenous (Choice B), and intranasal (Choice C) routes are not typically used for administering calcitriol as they may not provide the necessary absorption and metabolism required for its activation in the body.

Correct Answer: D

Rationale: Step-by-step rationale for why D (Spironolactone) is correct: 1. Spironolactone is an aldosterone receptor antagonist. 2. By competing with aldosterone for its cytosolic receptors, spironolactone inhibits its action. 3. This leads to decreased sodium reabsorption and potassium retention. 4. Spironolactone is used in conditions like heart failure, hypertension, and hyperaldosteronism. Summary of why other choices are incorrect: - A (Acetazolamide): Acts as a carbonic anhydrase inhibitor. - B (Furosemide): Inhibits the Na+/K+/2Cl- cotransporter in the loop of Henle. - C (Hydrochlorothiazide): Inhibits sodium reabsorption in the distal convoluted tubule by blocking the Na+/Cl- cotransporter.

Correct Answer: C

Rationale: Step-by-step rationale for why choice C (Aztreonam) is correct: 1. Monobactams are a class of antibiotics with a unique monocyclic beta-lactam ring structure. 2. Aztreonam is the only monobactam antibiotic listed among the choices. 3. Aztreonam is effective against aerobic Gram-negative bacteria. 4. It does not have cross-reactivity with beta-lactamases. Summary: A, B, and D are incorrect because they belong to different classes of antibiotics (penicillins, penicillin combinations, and carbapenems respectively), not monobactams.

Correct Answer: B

Rationale: The correct answer is B: PAS (para-aminosalicylic acid) because it is a second-line antimycobacterial drug used to treat drug-resistant tuberculosis. Isoniazid and rifampin are first-line agents, and streptomycin is an aminoglycoside antibiotic primarily used for treating bacterial infections, not specifically for mycobacterial infections. PAS is specifically indicated for multidrug-resistant tuberculosis cases, making it a second-line option.