Which of the Following Would Be Considered an Upstream Partner

Which of the following would be considered an upstream partner in a company's supply chain?

A) a firm that resells the finished product and shares the net sales with the producer
B) a firm that provides technical expertise in the production of the product
C) a firm that helps in marketing the product to consumers through the use of media
D) a firm that buys products in wholesale from the company
E) a firm that helps to exclusively market to other businesses