Which of the following situations can be approximated to a steady state heat transfer system?

A red hot steel slab $($having outside surface temperature as $1300$C$)$ exposed to the atmospheric air at $35$C

$10$ kg of dry saturated steam at $8$ kgf$/$cm$2$ flowing through a short length of stainless steel pipe exposed to atmospheric air at $35$C

Boiling brine kept in open vessel when the bottom surface temperature of the vessel is maintained constant at $180$C

A sub$-$cooled refrigerant liquid at $8$C flowing at the rate of $6$ Kg$/$minute through a copper pipe exposed to atmospheric air at $35$C