Comprehensive and Detailed Explanation: SFTP (Secure File Transfer Protocol)operates overport 22, usingSSH (Secure Shell) encryptionfor secure file transfers. Breakdown of Options: * A. 22-Correct answer.SFTP runs overSSH (port 22)for secure file transfers. * B. 80- Used forHTTP, not SFTP. * C. 443- Used forHTTPS (secure web traffic). * D. 3389- Used forRDP (Remote Desktop Protocol).