$($A$)$ How many sequencing instructions do you need to implement an if$-$then$-$else in MIPS assembly? $(0\mathrm{.}5$ point$)$

$($B$)$ Implement the following if$-$then$-$else in MIPS assembly. $(1\mathrm{.}5$ point$)$

else $\{$

$z=z+2$

$\}$

$\frac{\frac{?}{?}}{x}inR1,yinR2,zinR3$