The City of Cinnamon Hill operates a central motor pool as an internal service fund for the benefit of the city's other funds and departments, In the current year, this fund charged the Parks Department $30,000 for vehicle rental's. What account should the internal service fund use to record these charges? O a Interfund Exchanges. O b. Billings to Departments. O d. Interfund Transfers In. O d. Cost of Providing Peritals to Other Fund's and Units