Correct Answer: A

Rationale: During the repolarization phase of cardiac muscle tissue, potassium channels open while sodium channels close. This process is crucial for the cardiac muscle to return to its resting state after depolarization. Potassium moving out of the cell and sodium staying out helps reset the membrane potential and prepare the cell for the next depolarization phase. The influx of calcium is not the primary stimulus for repolarization in cardiac tissue; it is mainly involved in the depolarization phase. While electrical activity within the heart influences repolarization, the specific ion movements described in choice A are what physiologically drive repolarization. Cell membranes need to be in an active state during repolarization, not calm, to facilitate the necessary ion movements for muscle tissue to properly function.

Correct Answer: C

Rationale: The correct answer is C. In assessing a child for migraines, asking about food allergies is least likely to yield data that will confirm or rule out migraines as the cause of his headaches. Food allergies are unrelated to the typical symptoms and triggers of migraines, such as family history, associated symptoms like nausea and vomiting, and pain-free intervals between headaches. Therefore, in this scenario, focusing on food allergies is less relevant for identifying migraines as the cause of the boy's headaches.

Correct Answer: B

Rationale: The correct instruction the nurse should provide is to avoid taking nitrates while on sildenafil (Viagra). Combining sildenafil with nitrates can result in severe hypotension due to additive vasodilatory effects. Choice A is incorrect because sildenafil can be taken with or without food. Choice C is incorrect as there is no specific requirement to take sildenafil at bedtime. Choice D is incorrect as taking sildenafil with milk has not been shown to enhance its absorption.

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. This positioning helps reduce the risk of esophageal irritation and ensures adequate drug absorption. Choice B is incorrect because alendronate should be taken with water, not milk. Choice C is incorrect as there is no specific advantage to taking alendronate at bedtime. Choice D is incorrect because taking alendronate with food may interfere with its absorption.

Correct Answer: B

Rationale: The correct answer is B: 'vigilant adherence to the drug regimen.' When initiating oral contraceptive therapy, the success of preventing pregnancy relies heavily on the patient's commitment to following the prescribed regimen consistently. Compliance with taking the oral contraceptives as directed is crucial for their effectiveness. Choice A, 'current health status,' is not the primary factor for successful prevention of pregnancy with oral contraceptives. Choice C, 'knowledge of sexual health,' while important, is not the primary determinant of contraceptive efficacy. Choice D, 'risk factors for adverse effects,' though relevant for monitoring and managing side effects, is not the primary focus for ensuring contraceptive success.