Which of the following reduces the amount of data that must be transmitted on a network by keeping a copy of recently transmitted data in memory?

Latency refers to the delay in data transmission and does not reduce the amount of data transmitted on a network.

Compression reduces the size of data before it is transmitted, which lowers the volume of data, but it does not work by keeping a copy of recently transmitted data in memory to avoid future transmissions.

Caching involves storing copies of frequently accessed or recently transmitted data in a faster, closer memory location (like RAM). When data is requested, the system first checks the cache; if the data is present, it's served from the cache, eliminating the need to re-transmit the data across the network from its original source, thereby reducing network traffic.

Bandwidth is the maximum data transfer rate of a network connection and does not inherently reduce the amount of data that needs to be transmitted.