$Cu+H_2\quad\underrightarrow {heat}\quad Cu+x$, $ZnO+y\quad\underrightarrow{heat} \quad Zn+H_2O$, $2AgCl+H_2\rightarrow z+w$. The $z$ is

Question

$\begin{array}{1 1}(a)\;AgCl\\(b)\;2AgCl\\(c)\;2Ag\\(d)\;Ag\end{array}$