Final answer:
The 18-year-old female with an open head injury and a blood pressure of 180/120 is the highest priority in triage due to the immediate risks associated with traumatic brain injuries and the potential indication of increased intracranial pressure.
Step-by-step explanation:
In triage at the scene of a multiple-casualty incident, the goal is to prioritize patients based on the severity of their conditions and the urgency of their need for care to maximize the number of survivors. Of the patients listed, the one who would present with the highest priority for immediate treatment is the 18-year-old female with an open head injury, BP 180/120. Head and traumatic brain injuries can lead to immediate death and disability. This patient's high blood pressure could indicate increased intracranial pressure, making the situation time-sensitive, and therefore, she should be treated as the highest priority.