Givne boolean expression is $(\bar x\bar yz+yz+xz)$
taking $z$ as common
$= z(\bar x\bar y+y+x)$
applying distributive law $(a+bc=(a+b)(a+c))$
$= z((y+\bar y)(\bar x+y)+x)$
$\because (y+\bar y=1)$
$=(x+\bar x)+y$
$= z(1+y)$
$\because (1+x=1)$
$=z.1=z$
So option $C$ is correct.