Consider the following context$-$sensitive grammar:

$S$abBcd$|abcd$

$bBBb$

$aB$aaC

$CbbC$

$CcbDc$

$DccD$

$Dd$cEdd$|cdd$

$cEEc$

$bEbB$

$($a$)[3$ marks$]$ Give a derivation to show how the string $a^2{b}^2{c}^2{d}^2$ can be derived in the

grammar. You should ensure that each step of your derivation corresponds to the

application of a single rule of the grammar.

$($b$)[2$ marks$]$ Identify the language that is generated by this grammar.