$4.(10$ points$)$ To the left of each awk command below, write the number of the corresponding sed command and the letter of the corresponding grep$/$tr$/$sort$/\backslash (\backslash$mathcal$\{$G c$\}\backslash )$ c$.$ command. Assume no spaces at the beginning or end of input lines. If any is not possible, mark it with an $\text{'}$ X $\text{'}.$ The first one has been done for you.

$```$

a$)10$ E awk $\text{'}\{$print substr$($$$0,$length$($$$0),1)\}\text{'}$ d$)\_\_\_$ awk $\text{'}$NR

b$)\_\_\_$ awk $\text{'}/^[$Aa$]/\text{'}$

c$)\_\_\_$ awk 'length $>25\text{'}$

$1$ sed $\text{'}/...../$d$\text{'}$ A fgrep $-$v $\text{'}.\text{'}$

$2$ sed $\text{'}/\backslash ./$d$\text{'}$ B grep $-$E $\text{'}..\{25\}\text{'}$

$3$ sed $\text{'}5$q$\text{'}$ C grep $-$E $\text{'}$~$[0-9]+$$$\text{'}$

$4$ sed $\text{'}$s$/.*//\text{'}$ D grep $-$i $\text{'}`$a$\text{'}$

$5$ sed $\text{'}$s$/.*//\text{'}$ E grep $-$o $\text{'}.$$$\text{'}$

$6$ sed $\text{'}$s$/.*.//\text{'}$ F grep $-$o $\text{'}[^]*\text{'}$

$7$ sed $\text{'}$s$/^.\backslash (\backslash$ldots$..\backslash ).*/\backslash 1/\text{'},$ G grep $-$o $\text{'}[^]*$$$\text{'}$

$8$ sed $\text{'}$s$/\backslash (.*\backslash ).//\text{'}$ H grep $-$o $\text{'}^[^]*\text{'}$

$9$ sed $-$En $\text{'}/..\{25\}/$p$\text{'}$ I grep $-$v $......$

$10$ sed $-$e $\text{'}$s$/.*\backslash (.\backslash )/\backslash 1/\text{'},$ J grep $-$w $25$

$11$ sed $-$n $\text{'}/^[0-9][0-9]*$$$/$p$\text{'}$ K head $-5$

$12$ sed $-$n $\text{'}/^[$Aa$]/$p$\text{'}$ L sed $\text{'}/^$$$/$d$\text{'}$

$13$ sed $-$n p$\text{'}$ M tail $-5$

$```$