Which Metasploit payload includes simple upload and download functionality for moving files to and from compromised systems?

DLL inject is a code injection technique that loads a library into a running process's memory space and does not include any file transfer commands.

Upexec uploads a single executable to the target and executes it, providing one-directional upload functionality only - not bidirectional file transfer.

Meterpreter is actually the Metasploit payload that includes the 'upload' and 'download' commands for simple file transfer, making it the technically correct answer despite what the provided answer key indicates.

Note: Vncinject injects a VNC server into a process for remote desktop access and does not natively provide simple upload/download file transfer commands - Meterpreter (option C) is the Metasploit payload that specifically includes 'upload' and 'download' commands for moving files. This answer key appears to contain an error; option C is the technically accurate answer.