Which of the Following Best Describes a Tying Arrangement

Which of the following best describes a tying arrangement?

A) two companies jointly market their products of services
B) a seller requires the purchase of one product or service in order to be able to purchase a second product or service
C) a seller sets her price according to a market index
D) a seller offers a volume discount for purchases of large quantities
E) a seller refuses to deliver merchandise until payment has been received