Ethene on ozonolysis yields X. To prepare successive homologue of X, which of the following should be subjected to ozonolysis?

Oxidative ozonolysis of 2-butene in the presence of Zn or dimethyl sulphide forms acetaldehyde.

The reaction is as follows:
${\mathrm{CH}}_3-\mathrm{CH}=\mathrm{CH}-{\mathrm{CH}}_3+{\mathrm{O}}_3\stackrel{\mathrm{Zn} \mathrm{or} \mathrm{dimethyl} \mathrm{sulphide}}{\to }2{\mathrm{CH}}_3\mathrm{CHO}$

To prepare successive homologue of $\mathrm{X}$,  Butene – 2 should be subjected to ozonolysis

Hence the correct option is (D)