Correct Answer: D

Rationale: The classification system of congenital heart defects into acyanotic or cyanotic defects is problematic because children with acyanotic heart defects may develop cyanosis, complicating the differentiation. Cyanosis can occur in some acyanotic defects due to various reasons such as right-to-left shunting or decreased pulmonary blood flow, making the classification based solely on cyanosis misleading. Choice A is incorrect because while the classification may involve hemodynamics, the main issue lies in the potential for acyanotic defects to develop cyanosis. Choice B is incorrect as the ease of identifying children with cyanotic defects does not address the main problem with the classification system. Choice C is also incorrect as the presence of cyanosis is not the only factor determining the classification's validity.

Correct Answer: C

Rationale: In a child with suspected Addison disease, the presence of hyperpigmentation (bronzing of the skin) and hypotension are key clinical findings. Hyperpigmentation is due to increased ACTH stimulation, resulting in melanocyte stimulation. Hypotension occurs due to decreased aldosterone production and subsequent sodium loss. Choices A, B, and D are incorrect. Arrested height and increased weight are not typical of Addison disease; thin, fragile skin and multiple bruises are more indicative of conditions like Cushing's syndrome; blurred vision and enuresis are not typically associated with Addison disease.

Correct Answer: B

Rationale: Metatarsus adductus is a condition where the front part of the foot is turned inward. It is often caused by the baby's position in the womb, leading to pressure on the foot during fetal development. Choice A is incorrect as metatarsus adductus is not primarily caused by a genetic defect in the bones. Choice C is incorrect as the cause of metatarsus adductus is known to be related to intrauterine positioning. Choice D is incorrect as metatarsus adductus specifically pertains to the foot and not the hip.

Correct Answer: B

Rationale: During a vaso-occlusive crisis in sickle cell anemia, ensuring adequate hydration is crucial because it helps to reduce the viscosity of the blood and prevent further sickling of the cells. Administering oxygen may be necessary in some cases to improve tissue oxygenation, but hydration is the priority to prevent complications. Monitoring vital signs is important, but hydration takes precedence during a vaso-occlusive crisis. Administering pain medication is important for pain management but does not address the underlying issue of vaso-occlusion.

Correct Answer: B

Rationale: The correct answer is B: 'Dry the area between your toes thoroughly.' When educating an adolescent about tinea pedis, emphasis should be placed on keeping the feet dry, especially between the toes, to minimize the risk of fungal infection. Choice A is incorrect as keeping the feet moist can exacerbate the condition. Choice C is incorrect because nylon or synthetic socks can trap moisture, promoting fungal growth. Choice D is incorrect as walking barefoot in locker rooms increases the risk of contracting tinea pedis from contaminated surfaces.