Correct Answer: C

Rationale: Pure tone audiometry is an appropriate and effective screening test for hearing in a 5-year-old child, helping to assess the ability to hear various frequencies and volumes.

Correct Answer: A

Rationale: The correct answer is A: Transition from fetal to neonatal breathing. The most critical physiological change required of newborns at birth is the initiation of breathing. This transition is crucial for the newborn to start exchanging oxygen and carbon dioxide outside the womb, marking the beginning of their independent respiratory function. Choices B, C, and D are important aspects of newborn care but are not as immediately critical as the establishment of breathing for oxygenation and removal of carbon dioxide, which is essential for the newborn's survival and adaptation to extrauterine life.

Correct Answer: B

Rationale: When switching from intravenous to oral morphine, a higher oral dose is required to achieve equianalgesia due to significant metabolism from the first-pass effect. Choosing the same oral dose as the intravenous dose would provide less pain relief. Opting for a dose greater than the intravenous dose is necessary to achieve the same analgesic effect. Therefore, options A, C, and D are incorrect.

Correct Answer: B

Rationale: Morphine is the drug of choice for PCA in children because of its efficacy, safety profile, and rapid onset of action for pain management.

Correct Answer: C

Rationale: Osteosarcoma is typically treated with a combination of surgery and chemotherapy. This approach aims to remove the tumor and reduce the risk of metastasis. Amputation of the affected extremity may be necessary in some cases to ensure complete removal of the tumor. Intensive radiation is not the primary treatment for osteosarcoma, and bone marrow transplantation is not the standard treatment for this type of cancer.