The GET command is commonly used in HTTP (Hypertext Transfer Protocol), which is a part of the TCP/IP (Transmission Control Protocol/Internet Protocol) suite of protocols. Therefore, the answer is (a) TCP/IP. The GET command is used to retrieve data from a server, typically a webpage or a file, by sending a request to the server using the HTTP protocol. It is not directly related to FTP (File Transfer Protocol), MAC (Media Access Control), or ASP (Active Server Pages).