Final answer:
B) Working Capital Fund (WCF)
The Working Capital Fund (WCF) is used for billing services like rentals of medicinal cylinders when they are listed as separate line items.
Step-by-step explanation:
When services such as rentals of medicinal cylinders are listed as separate line items and are separately billed, the fund generally used for accounting is the Working Capital Fund (WCF). This fund is designed for revolving funds that operate on a commercial basis, providing an exchange of goods or services. It operates based on the principle of reimbursement for expenses, and expenses directly related to service provision, such as rentals, are typically billed to and paid for from the WCF.