One of the Assumptions on Which the Purchasing-Supplier Satisfaction Model

One of the assumptions on which the purchasing-supplier satisfaction model is based is that:

A) the satisfaction level cannot be assessed well enough to draw definitive conclusions.
B) the purchaser and supplier always have the same perceptions of the same relationship.
C) attempts to move to a different position fall only in the win-lose and win-win categories.
D) an unsatisfied party may use various tools to improve the relationship.
E) there are few tools and techniques available to move positions or improve stability.