When the lead time of the supplier is two weeks and weekly demand follows a normal distribution with average of $1000$ units and a standard deviation of $50,$ what is the demand during the lead time $($Sigma$\_$L$)?$

a$.$

Sigma$\_$L$=106\mathrm{.}8$

b$.$

Sigma$\_$L$=45\mathrm{.}9$

c$.$

Sigma$\_$L$=90\mathrm{.}5$

d$.$

Sigma$\_$L$=70\mathrm{.}7$