Which of the following reactions is the metal displacement reaction? Choose the right option.
$2Pb{(N{O_3})_2} \to 2PbO + 4N{O_2} + {O_2} \uparrow $
$$2KCl{O_3}\buildrel \Delta \over
\longrightarrow 2KCl + 3{O_2}$$
$$C{r_2}{O_3} + 2Al\buildrel \Delta \over
\longrightarrow A{l_2}{O_3} + 2Cr$$
$Fe + 2HCl \to FeC{l_2} + {H_2} \uparrow $
