Is $-$d $/$etc$/[$a$,$b$,$c$,$d$]???$

Is $-$d $/$etc$/[$a$-$d$]???$

Is $-$d$/$etc$/?[$abcd$]??$

Is $-$d $/$etc$/[$abcd$]*[$efgh$]$

Explain what the $4$th command in the list above is doing. Why did you get the results that you did? Could the $4$th command display the file $/$etc$/$echo $($if this file actually existed$)?$ Expain? Could the $3$rd command above list the file $/$etc$/$echo$?$ Explain.

Submit your answer for this task on the answer sheet as Answer $21.$