$[5$ marks$]$ This question involves Boolean expressions and logic circuits.

$($a$)$ Draw a truth table and write a Boolean expression that exactly matches the following circuit diagram.

$($b$)$ Draw a circuit diagram that is equal to the following Boolean expression. The diagram must reflect the expression exactly. In other words, the diagram must include the gates that exactly match the operators in the expression:

$(notxdarrnot(not{Y}^{{?}^{?}}Z))vvnotZ$