Correct Answer: D

Rationale: The correct answer is D: Active artificial immunity. A tetanus booster shot confers protection through active artificial immunity. Active immunity involves the body producing its antibodies in response to an antigen, providing long-lasting protection. In this case, the tetanus booster shot triggers the student's immune system to produce specific antibodies against tetanus toxins. Choices A, B, and C are incorrect because passive immunity does not involve the individual's immune system producing antibodies; instead, it involves the direct transfer of antibodies from another source (natural or artificial) for immediate, but temporary, protection.

Correct Answer: B

Rationale: Metaplasia is the replacement of one type of cell with another, which can occur in response to chronic irritation, such as from smoking. In this case, the respiratory tract cells being replaced by less mature squamous epithelium cells indicate metaplasia. Dysplasia refers to abnormal development or growth of cells, not replacement; hyperplasia is an increase in the number of cells, not a replacement; and coagulation is a process related to blood clotting, not cell replacement.

Correct Answer: C

Rationale: Natural killer cells are a type of lymphocyte that plays a crucial role in recognizing and eliminating virus-infected cells and cancerous cells. Neutrophils (Choice A) are a type of white blood cell involved in fighting infections, mainly through phagocytosis. Macrophages (Choice B) are another type of white blood cell that engulfs and digests cellular debris and pathogens. Langerhans cells (Choice D) are a type of dendritic cell found in the skin and mucosa, primarily involved in antigen presentation.

Correct Answer: A

Rationale: The correct answer is A. Tamoxifen increases the risk of venous thromboembolism. Patients should be educated about the signs and symptoms of blood clots, such as swelling, redness, and pain in the legs. Choices B, C, and D are incorrect because tamoxifen is not associated with causing hot flashes, weight gain, fluid retention, or decreasing the risk of osteoporosis.

Correct Answer: A

Rationale: The correct answer is A. Long-term HRT is associated with increased risks of cardiovascular events and breast cancer. These risks should be discussed with the patient to ensure they are informed about the potential adverse effects. Choice B is incorrect because HRT does not decrease the risk of osteoporosis; in fact, it may increase the risk of certain conditions like cardiovascular events. Choice C is incorrect as HRT is associated with an increased risk of venous thromboembolism, not a decreased risk. Choice D is incorrect because while HRT may have positive effects like improving symptoms of menopause, it is not primarily indicated for improving mood and energy levels.