Which command staff member approves the incident action plan and all requests pertaining to the ordering and releasing of incident resources?

D) Incident Commander

Explanation:

During every emergencies, incident commander has a similar power and responsibilities with the CEO of a business entity.

The incident commander need to ensure that every single members of the team managed to carried out their own role and the team able to fulfill the goals that were set before the operation.

Approving incident plan in this context is important to ensure that each individuals in the team understand what are expected to them. The resources management is important to ensure that the members had all the tools / materials they need to execute their strategy.