$F(x,y,z)=($x$\text{'}+$ z$\text{'})($x$\text{'}+$ z$)+$ x$\text{'}$yz$\text{'}$

a$-$ Draw the combinational circuit that directly implements the Boolean expression:

b$-$ For what values of $x,y,$ and z the output $($F$)$ will be $0?$ Justify your answer using a truth table.