Which of the following is an example of a unicast transmission?

Unicast transmission refers to the communication between one sender and one specific receiver. It is a one-to-one communication that ensures that the data is delivered to a single destination address. In this context, streaming a video to one user exemplifies unicast transmission because the video data is sent directly from the server to a single user’s device, ensuring that only that individual receives the information.

The other examples provided illustrate different types of transmission methods. Sending a group message to multiple users represents a multicast transmission since it involves sending data to a specific group of users rather than a single recipient. Broadcasting, such as making an announcement through a PA system, involves disseminating information to all possible recipients within an area, effectively reaching multiple users at once without targeting any specific one. Lastly, sharing a file with several users simultaneously is also a form of multicast or broadcast communication, as it implies that multiple users are the intended recipients of the same data simultaneously. Thus, streaming a video to one user is the only scenario that accurately depicts unicast transmission.