$.$ A supervisor fires a worker for violating work procedures. Several months before her termination, the worker had spoken for other employees in the unit in complaining about unsafe work conditions. HR is aware of the complaint. The worker is not a member of any union. What should HR do$?$

A$.$ Initiate an investigation. Being that this may fall under OSH Act

B$.$ Document the grounds for discharge.

C$.$ Conduct an exit interview with the employee.

D$.$ Override the supervisor's termination.