DiGeorge syndrome is a primary immune deficiency caused by:

Correct Answer: B

Rationale: DiGeorge syndrome is caused by a congenital lack of thymic tissue, which plays a crucial role in T cell development and maturation, leading to immune deficiency. Choice A is incorrect because DiGeorge syndrome primarily affects T cells, not B cells. Choice C is incorrect as it is too broad and not specific to the thymus. Choice D is incorrect as selective IgG deficiency is a different condition unrelated to DiGeorge syndrome.

Correct Answer: D

Rationale: The father's immune reaction to poison ivy is an example of cell-mediated immunity, specifically a type IV hypersensitivity reaction. In this type of reaction, sensitized T cells react to antigens, leading to inflammation and tissue damage. IgE-mediated reactions involve antibodies of the IgE class, commonly seen in allergic responses like anaphylaxis. Tissue-specific reactions target specific organs or tissues. Immune complex reactions involve immune complexes formed by antigens and antibodies that can deposit in tissues, leading to inflammation.

Correct Answer: D

Rationale: Innate resistance or immunity relies on the body's natural defenses like physical, mechanical, and biochemical barriers. These barriers act as the first line of defense against pathogens and do not involve memory (choice A). Innate immunity is present from birth and does not develop over an individual's later years (choice B). Additionally, innate immunity is a rapid and nonspecific process, not a slow and specific one (choice C). Therefore, the correct answer is D.

Correct Answer: A

Rationale: The correct statement to include in the nurse's teaching is that clomiphene induces ovulation by stimulating the release of gonadotropins, which in turn stimulate the ovaries. Choice B is incorrect because clomiphene does not induce ovulation by inhibiting gonadotropins. Choice C is also incorrect as clomiphene does not suppress ovulation by inhibiting gonadotropins. Choice D is inaccurate as clomiphene does not directly increase progesterone levels to maintain pregnancy.

Correct Answer: D

Rationale: The primary reason for prescribing testosterone therapy for osteoporosis in men is to restore testosterone levels, not specifically to increase bone density. Testosterone plays a crucial role in maintaining bone density, so by restoring testosterone levels, it indirectly helps in maintaining bone density. Choices A and B are partially correct but do not address the primary reason for testosterone therapy in this context. Choice C is incorrect as the main focus of testosterone therapy in osteoporosis treatment is not related to enhancing sexual performance.