Which of the following indicates an emergency requiring immediate attention?

An airway obstruction leading to unconsciousness is a critical situation that necessitates immediate intervention. When a patient experiences an airway blockage that results in loss of consciousness, their airway is compromised, and they are unable to protect it. This can quickly lead to hypoxia and respiratory failure if not resolved promptly. In such instances, the priority is to restore airflow to the lungs, which might involve techniques such as the Heimlich maneuver or intubation, depending on the severity and the context of the situation.

The other scenarios, while they may indicate some level of concern, do not present the same immediate life-threatening urgency. The ability to speak in full sentences typically indicates that a person is breathing adequately and has an open airway. An oxygen saturation below 95% does indicate some possible respiratory issue but is not an emergency unless accompanied by other critical signs or symptoms. Shortness of breath without distress can signify mild respiratory complications but does not necessarily require immediate action unless it escalates. Therefore, the presence of unconsciousness due to an airway obstruction is clearly the most urgent indicator of needing immediate care.