The answer that will complete the sentence above is change. It is because change has affected a lot of things as well as the area of marketing or business. With change, things changes completely or differently depending on the new things that are being discovered and are arising as time passes by. Supervisors are expected to learn to manage these changes for they are the ones who supervises their team and to do that, they should know how to adapt in these changes for the benefit of their team or company.
