Which of the Following Is the Best Definition of Vertical

Which of the following is the best definition of vertical merger?

A) A strategy in which one of the companies in the merger is a supplier or customer of the other
B) An approach by which firms move away from department-oriented organization and toward process-oriented team structures that cut across old departmental boundaries
C) The strategy of using the internet and word-of-mouth marketing to spread product information
D) Any activity that adds value to some input by transforming it into an output for an internal or external customer
E) The strategy of paying suppliers and distributors to perform certain business processes or to provide needed materials and resources