${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Cl}+\mathrm{Mg}\to \mathrm{x}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to }\mathrm{y}$ 

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Cl}\stackrel{{\mathrm{LiAlH}}_4}{\to }\mathrm{z}$,   then y and z are

The reactions are as follows:-

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Cl}+\mathrm{Mg} \to \underset{\mathrm{x}}{{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{MgCl} }\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to } \underset{\mathrm{y}}{{\mathrm{C}}_2{\mathrm{H}}_6}$

${\mathrm{C}}_2{\mathrm{H}}_5\mathrm{Cl}\stackrel{{\mathrm{LiAlH}}_4}{\to } \underset{\mathrm{z}}{{\mathrm{C}}_2}{\mathrm{H}}_6$

Here, y and z are same alkanes.

Alkanes are made up of hydrogen and carbon atoms that are arranged in a tree shaped structure with only single carbon-carbon bonds.

Hence, the correct answer option (C) same alkanes.