The BA should resolve the conflict between two stakeholders over which model to use for describing requirements by explaining that the models are complementary to each other. A model is a representation of a concept or system that is used to communicate or analyze it. Different models can be used for different purposes or audiences depending on their strengths and limitations. For example, an activity diagram can show the sequence and conditions of actions performed by actors or objects in a system, while a state diagram can show how an object changes its state in response to events. The BA should demonstrate how both models can be useful and relevant for describing different aspects of the requirements. Reference: : BABOK Guide v3, Section 4.5 : Activity Diagram vs State Diagram