Methotrexate is:

Correct Answer: B

Rationale: Methotrexate is a folic acid antagonist. It inhibits dihydrofolate reductase, leading to decreased DNA synthesis. This action makes it effective in treating cancer and autoimmune diseases. Purine antagonists target purine synthesis, antibiotics act on bacterial growth, and alkylating agents damage DNA to prevent cell division. Methotrexate's mechanism aligns with folic acid antagonism, making option B the correct choice.

Correct Answer: D

Rationale: The correct answer is D: Prazosin. Prazosin is an alpha-1 adrenergic blocker that can cause orthostatic hypotension, leading to dizziness and fainting when standing up rapidly. It works by dilating blood vessels, which can cause a sudden drop in blood pressure upon standing. Propranolol (A) is a beta-blocker and can cause dizziness but is less likely to cause orthostatic hypotension. Minoxidil (B) is a vasodilator that can cause rapid heart rate but not typically dizziness upon standing. Hydralazine (C) is a direct vasodilator that can cause reflex tachycardia but is less likely to cause orthostatic hypotension compared to alpha-1 blockers like Prazosin.

Correct Answer: C

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.

Correct Answer: D

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.