Consider achieving the best performance for the following instructions:

$1$ Add R$4,$ R$2,$ R$3$

$2.$ SW R$5,$ #$100($R$4)$

$3.$ LW R$6,$ #$200($R$4)$

$4.$ Sub $R7,R5,R6$

If forwarding is not allowed and the data hazards are solved by stall, the number of stall cycles in the pipeline are:

Select one:

a$.1$

b$.3$

c$.4$

d$.2$

e$.5$