The correct options are
B raising the realtive pressure of the steam
C raising the temperature
For the reaction,
C(s)+H2O⇌CO(g)+H2(g), ΔH is positive.
Hence, it is an endothermic reaction. So, on increasing the temperature, there is excess heat present in the reaction. This heat can be absorbed in an endothermic reaction, which is the forward reaction.
Also, if partial pressure of steam on the reactant side is raised, then the reaction constant will be less than the equilibrium constant. Hence, the reaction will move in forward reaction, so as to decrease the relative pressure of steam and increase the reaction constant to make it equal to equilibrium constant.