The drug acts by competitively blocking NaCl cotransporters in the distal tubule:

Correct Answer: C

Rationale: Rationale: Hydrochlorothiazide blocks NaCl cotransporters in the distal tubule, reducing sodium reabsorption and increasing diuresis. Acetazolamide inhibits carbonic anhydrase in the proximal tubule. Furosemide inhibits the Na-K-2Cl cotransporter in the thick ascending limb. Spironolactone is a mineralocorticoid receptor antagonist acting on the principal cells of the collecting duct. Therefore, the correct answer is C, as it directly targets the distal tubule's mechanism of sodium reabsorption.

Correct Answer: B

Rationale: The correct answer is B: Isoniazid. It is a first-line antimycobacterial drug used for treating tuberculosis. It targets the mycobacterial cell wall synthesis, specifically inhibiting mycolic acid production. This makes it effective against Mycobacterium tuberculosis. PAS (A) is a second-line drug with a different mechanism. Kanamycin (C) is also a second-line drug used for drug-resistant TB. Pyrazinamide (D) is a first-line drug, but it works by a different mechanism compared to isoniazid.

Correct Answer: D

Rationale: The correct answer is D: Niclosamide. Niclosamide is a salicylamide derivative used to treat tapeworm infections. This drug works by disrupting the mitochondrial function of parasites. Explanation: 1. Praziquantel (A) is used to treat schistosomiasis, not a salicylamide derivative. 2. Piperazine (B) is used to treat roundworm infections, not a salicylamide derivative. 3. Mebendazole (C) is an anthelmintic used to treat various worm infections, not a salicylamide derivative. In summary, Niclosamide is the correct choice as it is a salicylamide derivative specifically used for tapeworm infections, while the other options are used for different types of worm infections.

Correct Answer: D

Rationale: The correct answer is D: All of the above. Cytoprotectors help protect healthy cells from damage caused by cancer treatment. Bone marrow growth factors aid in stimulating the production of blood cells, which can be suppressed during cancer treatment. Antimetastatic agents help prevent the spread of cancer to other parts of the body. Therefore, all these groups of drugs are used as subsidiary medicines in cancer treatment to support the primary treatment and manage side effects. Choices A, B, and C are incorrect individually because each group plays a specific role in supporting cancer treatment, making the combination of all three necessary for comprehensive care.

Correct Answer: D

Rationale: Step 1: Identify the patient's condition as ventricular arrhythmia. Step 2: Choose a drug effective for ventricular arrhythmias, like Lidocaine. Step 3: Lidocaine is a class Ib antiarrhythmic drug that acts quickly on ventricular tissue. Step 4: Sotalol (A) is a non-selective beta blocker, not ideal for ventricular arrhythmias. Step 5: Flecainide (B) is a class Ic antiarrhythmic drug more suitable for supraventricular arrhythmias. Step 6: Mexiletine (C) is a class Ib antiarrhythmic, but lidocaine is preferred for acute ventricular arrhythmias.