Correct Answer: B

Rationale: The correct answer is B: 'Present in various sizes.' Anisocytosis refers to erythrocytes that are present in various sizes, indicating an abnormality in the uniformity of red blood cell size. Choice A is incorrect because anisocytosis does not refer to the color of erythrocytes. Choice C is incorrect as anisocytosis does not involve the shape of erythrocytes. Choice D is incorrect as anisocytosis does not determine the lifespan of erythrocytes.

Correct Answer: A

Rationale: The correct teaching point that the physician should include when explaining Duchenne muscular dystrophy to the parents is that 'Your child may develop breathing difficulties as the disease progresses.' Duchenne muscular dystrophy is a progressive condition that affects muscle strength, including respiratory muscles, leading to breathing difficulties as the disease advances. Choice B is incorrect because while physical therapy and exercise can help maintain muscle function and mobility, they do not cure the condition. Choice C is incorrect because Duchenne muscular dystrophy is a genetic disorder with no known cure. Choice D is incorrect as Duchenne muscular dystrophy is primarily characterized by a lack of dystrophin protein due to genetic mutations, not inflammation in the muscles.

Correct Answer: D

Rationale: The correct answer is D: Docosanol (Abreva). Docosanol is an over-the-counter topical cream commonly used to treat cold sores caused by the herpes simplex virus. It works by inhibiting viral fusion to host cell membranes, reducing the spread of the virus. Ganciclovir (Choice A) is an antiviral medication used for the treatment of cytomegalovirus infections. Valacyclovir (Choice B) and Famciclovir (Choice C) are prescription antiviral medications used to treat herpes simplex virus infections but are not typically available over-the-counter like Docosanol.

Correct Answer: B

Rationale: The primary role of cytokines in maintaining homeostasis is to perform a regulatory function in the development of diverse blood cells. Cytokines act as signaling molecules that regulate the immune response and hematopoiesis. Choice A is incorrect because cytokines do not perform phagocytosis; they regulate immune responses. Choice C is incorrect because while cytokines are involved in the formation of some blood cells, they are not considered the basic 'building blocks' of all blood cells. Choice D is incorrect because cytokines are not formed in response to antibodies, but rather play a role in the immune response to various stimuli.

Correct Answer: C

Rationale: The correct answer is C: Proliferation of T cells. The thymus gland is responsible for the maturation and proliferation of T cells, which play a crucial role in adaptive immunity. Option A, differentiation of B cells, is incorrect because B cell maturation primarily occurs in the bone marrow. Option B, production of natural killer (NK) cells, is incorrect as NK cells are mainly produced in the bone marrow and lymph nodes. Option D, filtration of antigens from the blood, is incorrect as antigen filtration is not a primary function of the thymus gland.