Which command is used to output any text provided to it?

The command used to output any text provided to it is "echo." This command is primarily utilized in shell scripting and command-line environments to display a line of text or a variable value. For example, by using the command 'echo Hello, World!', the terminal will output the text "Hello, World!" directly to the screen.

In contrast to other options, "cat" is used to concatenate and display the contents of files rather than just outputting simple text. The command "ls" lists directory contents and does not output arbitrary text. Meanwhile, "whoami" returns the current user's username, which is specific to the system's context and not an arbitrary text output command. Therefore, "echo" is the most appropriate choice for displaying any text provided to it.