Correct Answer: D

Rationale: The correct answer is D because screaming and thrashing his arms and legs are indicative behaviors of discomfort or pain in young children. The child's actions suggest a higher likelihood of experiencing postoperative pain and necessitate further evaluation. Choices A, B, and C do not exhibit overt signs of distress or discomfort associated with pain, making them less likely candidates for postoperative pain assessment.

Correct Answer: A

Rationale: In the case of severe isotonic dehydration, the initial fluid of choice is 0.9% normal saline. This solution is preferred because it helps to restore both fluids and electrolytes effectively. Options B, C, and D are not suitable for the initial management of severe isotonic dehydration. D5 0.2% (1/4) normal saline (Choice B) is a hypotonic solution and might worsen the imbalance. D5W (Choice C) is a hypotonic solution that does not contain electrolytes essential for rehydration. Albumin (Choice D) is a colloid solution used for specific indications like hypoproteinemia or hypoalbuminemia, not for initial rehydration in severe dehydration.

Correct Answer: D

Rationale: Conditions like oliguric renal failure, increased intracranial pressure, and mechanical ventilation significantly alter fluid requirements in children. These conditions either restrict fluid output or require careful fluid management to avoid worsening the condition.

Correct Answer: A

Rationale: Human milk is preferred, even for preterm infants, because it contains essential nutrients and antibodies that are particularly beneficial for their growth and development. Choice B is incorrect because human milk is rich in essential nutrients necessary for preterm infants. Choice C is incorrect as commercial infant formulas do not provide the same benefits as human milk. Choice D is incorrect as specialized formulas are available to meet the unique nutritional needs of preterm infants, but human milk remains the optimal choice.

Correct Answer: C

Rationale: Giardia lamblia is a protozoan parasite known to cause acute diarrhea, often through contaminated water or food. Shigella, Salmonella, and E. coli are bacterial pathogens that also cause diarrhea but are not parasites.