Correct Answer: B

Rationale: Cytotoxic T cells are the key players in cell-mediated immunity as they directly attack cells displaying specific antigens. Lymphokine-producing cells (Choice A) are involved in cytokine production, while Helper T cells (Choice C) assist in activating other immune cells. Macrophages (Choice D) are phagocytic cells that engulf and digest pathogens, but they are not the primary cells responsible for directly attacking cells with specific antigens in cell-mediated immunity.

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: D

Rationale: The correct answer is IgM. IgM is the first immunoglobulin to appear in response to a new antigen. It is produced initially during the primary immune response. IgA is mainly found in mucosal areas and secretions. IgG is produced in a secondary immune response and is the most abundant immunoglobulin in the bloodstream. IgE is involved in allergic reactions and parasitic infections, not the initial response to a new antigen.

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: 'It decreases bone resorption and increases bone density.' Raloxifene, as a selective estrogen receptor modulator (SERM), works by reducing bone resorption (breakdown) and maintaining or increasing bone density. This mechanism helps in preventing further bone loss and can even increase bone mass. Choices A, C, and D are incorrect. Raloxifene does not stimulate the formation of new bone (choice A), increase calcium absorption in the intestines (choice C), or increase the excretion of calcium through the kidneys (choice D).