Answer:
Option C; VIDEOCONFERENCING.
Explanation:
Video conferencing is a technology that allows users in different locations to hold face-to-face meetings without having to move to a single location together.
Videoconferencing may be used to announce significant changes at a company, such as promotions or to present information in an interactive way that allows all participants to engage in discussion about what they see on screen.
Since the corporation's employees are spread all over the world and the senior management are keen on capturing and gauging the emotional joy and delight on the faces of those promoted, therefore, the most appropriate method in announcing the promotions would be VIDEOCONFERENCING.