Which of the following is water-gas shift reaction?

The mixture of $\mathrm{CO}$  and ${\mathrm{H}}_2$ is called as water gas. As the mixture of $\mathrm{CO}$ and ${\mathrm{H}}_2$ is used for the synthesis of methanol and a number of hydrocarbons, it is also called 'syn gas' or synthesis gas.

The process of producing 'syn gas' from coal is called coal gasification.

$\mathrm{C}\left(\mathrm{s}\right) + {\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right) \to \mathrm{CO}\left(\mathrm{g}\right) + {\mathrm{H}}_2\left(\mathrm{g}\right)$

The production of dihydrogen can be increased by reacting carbon monoxide with steam in the presence of iron chromate as a catalyst.

${\mathrm{CO}}_{\left(\mathrm{g}\right)} + {\mathrm{H}}_2{\mathrm{O}}_{\left(\mathrm{g}\right)} \to {\mathrm{CO}}_{2\left(\mathrm{g}\right)} + {\mathrm{H}}_{2\left(\mathrm{g}\right)}$

This is called water gas shift reaction.