Which of the following commands copies the running configuration to a TFTP server?

The command that copies the running configuration to a TFTP server is "copy run tftp." In Cisco IOS, this command initiates the process of transferring the current configuration from the router or switch's active memory (running configuration) to a TFTP server for backup or recovery purposes.

When executing this command, you would typically need to specify the IP address of the TFTP server and the filename you want to use for the saved configuration. This action is essential for network management, as it allows network administrators to ensure they have a recent copy of configurations stored safely outside of the device, which can be critical for disaster recovery or when making significant changes to network settings.

The other options refer to different configurations or data management tasks. For instance, "copy startup running" typically is used to copy the startup configuration to the running configuration, ensuring that any settings saved in the startup configuration are applied to the active device configuration. "copy running startup" does the inverse, saving the current running configuration back to the startup configuration file, making it persist through a reboot. Lastly, "copy tftp run" would imply obtaining a configuration file from a TFTP server and applying it to the running configuration, which is a different operation altogether.