A system shows high utilization of swap space but low utilization of physical memory. Which of the following commands should an administrator run to free up usable swap space?

mkswap reformats a device as swap space, which is a destructive operation used during initial setup - it does not free existing swap data or move it back to RAM.

'free' is a read-only display command that shows memory statistics and takes no action; running swapon -a afterward would only attempt to enable swap again without clearing it.

Running 'swapoff -a' disables all swap partitions and forces the kernel to move all swapped-out pages back into physical memory, which is currently available. Running 'swapon -a' immediately after re-enables all swap partitions in a clean, empty state. The '&&' operator ensures swapon only runs if swapoff succeeds, preventing swap from being re-enabled before data is fully migrated.

The order is reversed - enabling swap before disabling it would not free the existing swap contents, and the semicolon means swapoff would run after swapon regardless of success, potentially corrupting state.