Final answer:
The correct answer is A) Incident Commander. The Incident Commander has the authority to manage incident operations and coordinate additional SIO assistance.
Step-by-step explanation:
The request for additional Scene of Incident (SIO) assistance, whether preplanned or spontaneous, should go through the Incident Commander. The Incident Commander is responsible for the management of all incident operations and is the individual with the authority to request and allocate resources, including additional SIO assistance. This centralized approach ensures that additional support is coordinated and integrated into the overall response effectively and efficiently.