正解:C
Explanation
A load balancer is a device or software that distributes network traffic across multiple servers or resources, such as web server farms, to optimize performance, reliability, and scalability. A load balancer controls the flow of users connecting to web server farms and prevents overutilization on any individual server by using various algorithms, such as round robin, least connections, or weighted distribution. A load balancer can also provide health checks, failover, caching, compression, encryption, and other features to enhance the user experience and security.