$28.$ A process has a Cp equal to $3\mathrm{.}5.$ Determine the standard deviation of the process if the design specifications are $16\mathrm{.}08$ inches plus or minus $0\mathrm{.}42$ inches.

A$.0\mathrm{.}02$

B$.0\mathrm{.}04$

C$.0\mathrm{.}21$

D$.0\mathrm{.}84$

E$.0\mathrm{.}24$