Which component primarily responds to requests for data transfer in a network?

The correct choice is the server, as it is specifically designed to respond to requests from clients in a network. A server hosts data, services, or applications and waits for requests from client devices, such as computers or mobile phones. When a client makes a request for resources, such as a web page or file, the server processes that request and sends back the appropriate data.

In contrast, while clients initiate these requests, nodes refer more generally to any device connected to the network, which can include both servers and clients. Routers play a different role, as they are responsible for directing the traffic between different networks rather than managing and responding to data requests directly. Thus, the server is the key component in handling data transfer requests from clients.