Which of the following reactions is the metal displacement reaction? Choose the right option.

A metal displacement reaction is a type of reaction where a more reactive metal displaces a less reactive metal from its compound (usually an oxide or salt).In option D, Aluminium ($\text{Al}$) is more reactive than Chromium ($\text{Cr}$). Thus, $\text{Al}$ displaces $\text{Cr}$ from its oxide ${\text{Cr}}_2{\text{O}}_3$:
$${\text{Cr}}_2{\text{O}}_3+2\text{Al}⟶{\text{Al}}_2{\text{O}}_3+2\text{Cr}$$
Option A is a non-metal displacement (displacing Hydrogen). Options B and C are decomposition reactions.