Final answer:
The security guard should close off the area and direct people and vehicles away to preserve the crime scene and await law enforcement to handle evidence and witness interrogation.The correct option is A.
Step-by-step explanation:
When a security guard is dispatched to an incident where a serious criminal offence has occurred and the offender has left the area, with the police on their way but not yet present, the guard's first response should be to close and cordon off the area and direct people and vehicles away from the scene (Option A).
This is important to preserve the integrity of the potential crime scene and to prevent contamination of any physical evidence.
The guard should also be observant and take note of any details that may later assist law enforcement but should not attempt to collect evidence or interrogate witnesses, as these actions could compromise the investigation. The correct option is A.