Which of the following commands are used to view memory usage? (Choose TWO correct answers.)

There is no standard Linux command named 'memory'; running it results in a command-not-found error on a default Linux system.

The top command provides a real-time, dynamic view of running processes including each process's memory and CPU consumption, as well as a summary of total and available memory at the top of its display. The free command is dedicated specifically to displaying total, used, free, shared, and available physical and swap memory in a concise tabular format. Both are standard tools available on virtually all Linux distributions for monitoring memory.

The ps command reports a snapshot of current processes and their states but is not primarily used for viewing overall system memory usage statistics.

The nice command is used to set or adjust the scheduling priority (niceness value) of a process and has no function related to displaying memory usage.