A process has three consecutive steps with the following reliabilities:Step A $-0\mathrm{.}94$ Step B $-0\mathrm{.}94$ Step C $-0\mathrm{.}80$A back$-$up is added to Step C$.$ What is the resulting reliability for the system? Choose the closest answer$\mathrm{.}0\mathrm{.}7050\mathrm{.}8460\mathrm{.}8640\mathrm{.}7320\mathrm{.}7180\mathrm{.}833$