What does it mean to be a medium of exchange?

Which of the following is true about presentation methods for providing training? audiovisual techniques are most effective when they are used alone. mobile technologies include training methods such as on-the-job training, simulations, business games and case studies, behavior modeling, interactive video, and web-based training that require the trainee to be actively involved in learning. the typical users for teleconferencing include employees who are part of a workforce that spends most of its time traveling, visiting customers or various company locations and has limited time available to spend in traditional training activities. webcasting involves classroom instructions that are provided online through live broadcasts. classroom instruction is no longer a popular training method because of new technologies such as interactive video and computer-assisted instruction.