The advantage of using multicast in the network is that

Multicast is a method of data transmission in which a single stream of data is sent from a source to multiple destinations simultaneously. This technique is especially useful in video surveillance because it allows multiple viewers to receive the same video stream without duplicating the data sent across the network. In other words, the video stream only needs to be sent once from the camera, even though there are multiple viewers, reducing network bandwidth usage. This makes option C correct. For more detailed information, refer to Axis Communications' official documentation on network video fundamentals and multicast usage.