What is your standard deviation of demand during lead time if your average lead time $=5$ days, standard deviation of demand $=4,$ average demand is $12,$ and standard deviation of lead time is $1\mathrm{.}2$ days.

$16\mathrm{.}95$

$15\mathrm{.}34$

$14\mathrm{.}39$

$13\mathrm{.}57$