$[15$ points$]$ Assume that we are debating whether to implement operating system functionalities $\backslash (\backslash$mathrm$\{$X$\},\backslash$mathrm$\{$Y$\}\backslash ),$ and Z as user$-$space programs or not. Based on the following facts, provide opinions on whether implementing each of these functionalities as a user$-$level program would be a good idea $($give your opinions separately for X$,$ Y$,$ and $\backslash ($ Z $\backslash )).$ Remember to provide the reasons as well.