Which of the variables is$/$are classified as $($a$)$ discrete variable$($s$)?$

Table$1$: A selection of variables from a database

$\backslash$table$[[\backslash$table$[[$Length of service$],[($months$)]],\backslash$table$[[$Home$],[$language$]],\backslash$table$[[$Distance to$],[$work $(km)$