Which command is used to view the current date and time on a Linux system?

The command used to view the current date and time on a Linux system is the "date" command. This command retrieves and displays the system's current date and time in a default format that can easily be read by users. It can also be modified with various options to customize the output format, allowing users to present the date and time in different ways as needed.

The other choices do not exist as standard commands in Linux for this purpose. "datetime" is not a recognized command, and while "time" does exist, it is primarily used to measure the duration of command execution rather than to display the current time. Lastly, "currenttime" is also not a command available in the standard Linux command set to provide date and time information. Thus, the "date" command is the correct and most commonly used tool for this task in a Linux environment.