Correct Answer: C

Rationale: The correct answer is C. Oral contraceptives can be less effective when taken with certain antibiotics as they may interfere with the contraceptive's efficacy, potentially leading to decreased effectiveness. Therefore, patients should be advised to use additional contraception methods if they are also taking antibiotics. Choice A is incorrect because while oral contraceptives are highly effective, they are not 100% foolproof. Choice B is incorrect as oral contraceptives may take some time to reach their full effectiveness after starting. Choice D is incorrect since taking oral contraceptives with food does not necessarily impact their effectiveness.

Correct Answer: C

Rationale: The correct answer is C. Viruses replicate their genetic material inside host cells, which is a fundamental aspect of their life cycle. Choice A is incorrect because viruses contain either RNA or DNA. Choice B is incorrect as viruses cannot reproduce independently and rely on host cells for replication. Choice D is incorrect as viruses are not easily killed by antimicrobials due to their unique structure and mechanisms of infection.

Correct Answer: A

Rationale: The correct answer is A. Alendronate should be taken with a full glass of water, and patients should remain upright for at least 30 minutes to prevent esophageal irritation and ensure proper absorption. Taking the medication at bedtime (choice B) is not recommended as it can lead to esophageal irritation when lying down. Taking the medication with milk (choice C) is incorrect as it may interfere with the absorption of alendronate. Taking the medication with food (choice D) is not recommended as it may reduce the effectiveness of the medication.

Correct Answer: C

Rationale: After the administration of interferon alfa-2b, the patient may develop flu-like symptoms as an adverse effect. Flu-like symptoms are commonly associated with interferon therapy, including fever, chills, fatigue, and muscle aches. These symptoms usually subside over time. Options A, B, and D are not typically associated with interferon alfa-2b administration. Profound diaphoresis is excessive sweating, decreased level of consciousness indicates neurological issues, and cyanosis and pallor suggest circulatory or respiratory problems, none of which are expected adverse effects of interferon alfa-2b.

Correct Answer: A

Rationale: The correct answer is A. Sildenafil is contraindicated in patients taking nitrates due to the risk of severe hypotension. Nitrates and sildenafil both cause vasodilation, leading to a synergistic effect that can result in a dangerous drop in blood pressure. Choices B, C, and D are incorrect because there is no specific contraindication for taking sildenafil with food, having a history of hypertension, or taking it with grapefruit juice. The main concern is the concurrent use of nitrates with sildenafil.