Final answer:
In an emergency, oral cavity bleeding should be managed first due to the potential for airway obstruction, which poses a more immediate threat to life than bilateral femur fractures.
Step-by-step explanation:
In emergency situations, care should prioritize injuries or conditions based on the immediate threat they pose to life. Oral cavity bleeding could be indicative of a problematic airway or could cause the patient to aspirate on blood, leading to a compromised airway which is a life-threatening emergency. On the other hand, while bilateral femur fractures are serious and require medical attention, they pose less immediate risk to life compared to a compromised airway. Therefore, the oral cavity bleeding should be managed FIRST before addressing the bilateral femur fractures.