‘z’ cannot be directly prepared from its elements conveniently.The best route to prepare ‘z’ is

 $\mathrm{x}+\text{C}+{\text{Cl}}_2\underset{ }{\overset{600-800\text{K}}{\to }}\mathrm{y}\underset{ }{\overset{{\text{LiAlH}}_{\text{4}}}{\to }}\mathrm{z}$. Then $\mathrm{x},\mathrm{y},\mathrm{z}$ are 

• A

  ${\text{CaO,\hspace{0.17em}CaCl}}_{\text{2}}{\text{,\hspace{0.17em}CaH}}_{\text{2}}$

• B

  ${\text{BeO,\hspace{0.17em}\hspace{0.17em}BeCl}}_{\text{2}}{\text{,\hspace{0.17em}\hspace{0.17em}BeH}}_{\text{2}}$

• C

  ${\text{BaO,\hspace{0.17em}\hspace{0.17em}BaCl}}_{\text{2}}{\text{,\hspace{0.17em}\hspace{0.17em}BaH}}_{\text{2}}$

• D

  ${\text{SrO,\hspace{0.17em}\hspace{0.17em}SrCl}}_{\text{2}}{\text{,\hspace{0.17em}\hspace{0.17em}SrH}}_{\text{2}}$