When Is the Bill Onscreen Form Used to Record a Vendor

When is the Bill onscreen form used to record a vendor transaction in QBO?

A) It is used to record services for which a company has been billed for and agreed to pay later.
B) It is used to record expenses a company pays for at the time it receives the product or service.
C) It is used when a vendor gives a refund or reduction in a bill for what is owed to the vendor.
D) It is used to record a credit or a reduction in the charges owed to the vendor.