Show that the following operations are closed for regular languages!

$($a$)$ Set difference $($L$1\backslash$L$2$

$)$

$($b$)$ Reversal $($L

R

$1=$

w

R

$|$w in L$1$

$)$

$($c$)$ Intersection $($L$1\backslash$cap L$2$

$)$