$(6)$ Consider the following langrage $L_1=$ and $L_2=\{\}$ which ore of the folming represent

$L_1^{**}{L}_1^{**}{L}_2^{**}?,(5)$

$($a$)\{in\}$

$($b$)\{lon,1\}$

$($c$)$

$($d$)1^{**}$

Rearite

$(7)$ Anytherg concatenate cirtu $$ is a $$

$(5)$

Example.