Correct Answer: D

Rationale: The correct answer is D: Serum immunoglobulin E (IgE) level. An elevated serum IgE level is commonly associated with atopic dermatitis, reflecting an allergic response. Choice A, erythrocyte sedimentation rate, is a nonspecific test for inflammation and not specific to atopic dermatitis. Choice B, potassium hydroxide prep, is used to diagnose fungal infections like tinea versicolor, not atopic dermatitis. Choice C, wound culture, is not typically indicated for the diagnosis of atopic dermatitis as it is a chronic inflammatory skin condition rather than an infectious process.

Correct Answer: A

Rationale: The inability to copy a square at 3 years old indicates a potential developmental delay in fine motor skills. At this age, children should be able to copy basic shapes like circles and crosses. Hopping on one foot is typically expected around the age of 4, catching a ball reliably around 5, and using a spoon effectively by 2-3 years old. Therefore, choices B, C, and D are not as indicative of a developmental delay at 3 years old as the inability to copy a square.

Correct Answer: C

Rationale: The correct answer is C, Chickenpox (varicella). Chickenpox is a viral disease characterized by a highly pruritic rash that typically starts on the abdomen and then spreads to other parts of the body, including the face and proximal extremities. It can lead to complications such as pneumonia and encephalitis. Rubella (German measles) presents with a mild rash and swollen lymph nodes; Rubeola (measles) also presents with a rash but starts on the face before spreading downwards; Scarlet fever is caused by Group A Streptococcus bacteria and is characterized by a rash, fever, and sore throat.

Correct Answer: A

Rationale: A webbed neck is a key feature seen in Turner syndrome, a genetic condition that occurs in females due to a complete or partial absence of one of the X chromosomes. This physical trait is caused by excess skin on the neck, giving it a webbed appearance. Microcephaly (Choice B) is a condition characterized by a smaller than average head size and is not typically associated with Turner syndrome. Gynecomastia (Choice C) refers to breast enlargement in males and is not a common finding in Turner syndrome, which affects females. Cognitive delay (Choice D) is not a specific characteristic of Turner syndrome, as the syndrome primarily affects physical development and may not necessarily impact cognitive abilities.

Correct Answer: D

Rationale: The most accurate way to determine a therapeutic dose for children is based on their weight rather than age. Weight-based dosing accounts for individual variations in drug metabolism and distribution, ensuring a more precise and safer medication administration. Choices A, B, and C are incorrect as they do not address the importance of weight-based dosing in children, potentially leading to inappropriate dosing and safety concerns.