Correct Answer: C

Rationale: The most appropriate course of action for the nurse is to observe the hairline and scalp for possible signs of lice. The student's behavior of excessively rubbing her scalp raises concerns about a potential infestation, making it necessary to look for signs firsthand. Contacting the parents or the physician should be considered after observing for signs of lice to provide more information and take appropriate action. Requesting a private evaluation from the parents may not be required initially, as lice infestation is a common concern among children and observing for signs is the immediate step to address the situation.

Correct Answer: B

Rationale: The correct answer is that chemotherapy is a systemic treatment affecting both tumor and normal cells. 5-FU, as an antimetabolic drug, inhibits DNA synthesis and interferes with cell replication systemically. It affects all rapidly growing cells, including malignant and normal ones. This drug is used as adjuvant therapy for various cancers.
Choice A is incorrect because chemotherapy affects both tumor and normal cells, not just tumor cells.
Choice C is incorrect as chemotherapy has been proven effective in treating cancer.
Choice D is incorrect because chemotherapy often causes side effects like bone marrow depression, anorexia, stomatitis, nausea, and vomiting.

Correct Answer: C

Rationale: Certain foods like broccoli, oranges, dark greens, and dark yellow vegetables can help improve defense mechanisms by enhancing the immune system and overall health. While these foods can boost defense mechanisms, they are not a cure for diseases, do not balance body functions, and are not intended to solely supplement vitamin intake, which may be necessary in some cases.
Therefore, the correct answer is defense mechanisms as these foods strengthen the body's ability to fight off illnesses and maintain health.

Correct Answer: B

Rationale: Zofran is a serotonin antagonist commonly used to relieve nausea and vomiting by blocking serotonin receptors. Metoclopramide (Reglan) acts on dopamine receptors, hydroxyzine (Vistaril) is an antihistamine, and prochlorperazine (Compazine) is a dopamine antagonist. While these medications can also be used for nausea and vomiting, they do not primarily function as serotonin antagonists like ondansetron.

Correct Answer: A

Rationale: Levothyroxine (Synthroid) is the preferred medication for hypothyroidism due to its chemical stability, nonallergenic properties, and convenient once-daily oral administration. It is safe and effective with minimal side effects when appropriately dosed.
Choice B is incorrect because while Levothyroxine is available in various concentrations, it is not the reason it is the drug of choice; the primary reason is its stability and nonallergenic nature.
Choice C is wrong as Levothyroxine (T4) is not a prodrug of T3; it is converted to T3 in the body. Option D is inaccurate because Levothyroxine has a long half-life (around 7 days), enabling once-daily dosing, as opposed to a short half-life.