$1.$ The Boolean expression $x=AB+CD$ represents

$($a$)$ two ORs ANDed together

$($b$)$ an EX$-$OR

$($c$)$ two ANDs ORed together

$($d$)$ four$-$input OR gate

$($e$)$ four $-$input AND gate

$2.$ The Boolean expression $Y=A^{\text{'}}{B}^{\text{'}}+AB$ is

$($a$)0$

$($b$)1$

$($c$)$ an EX$-$OR

$($d$)$ all of the above

$($e$)$ none of the above

$3.$ The Boolean expression $W=A{B}^{\text{'}}+B{A}^{\text{'}}$ is

$($a$)0$

$($b$)1$

$($c$)$ an EX$-$NOR

$($d$)$ all of the above

$($e$)$ none of the above

$4.$ The Boolean expression $Z=(CD{)}^{\text{'}}+DC$ is

$($a$)$ a NAND gate

$($b$)$ a NOR gate

$($c$)1$

$($d$)$ an EX$-$OR

$($e$)$ none of the above