A user checks the free space in a folder on their local computer, Y:$\backslash$BusReports$,$ and notices that $3$ GB of disk space is reported as available. When the user checks free space in Y:$\backslash$BusReports$\backslash$Archive$,$ he notices that $50$ GB of disk space is reported as available. The difference in available disk space is probably because the folder Y:$\backslash$BusReports$\backslash$Archive is $\_\_\_\_\_.$

a$.$ a mount point

b$.$ encrypted

c$.$ archived

d$.$ dynamic

e$.$ compressed