In which reaction, hybridisation of underlined atom remains unchanged ?

• A

  $\text{ Combustion of }\underset{\_}{\mathrm{C}}{\mathrm{H}}_4$

• B

  $\text{ Solidification of }\underset{\_}{\mathrm{P}}{\mathrm{Cl}}_5\text{ vapour }$

• C

  $\underset{\_}{\mathrm{S}}{\mathrm{iF}}_6\text{ vapour is passed through liq. }\mathrm{HF}$

• D

  $\underset{\_}{\mathrm{Al}}(\mathrm{OH}{)}_3\text{ ppt. dissolves in }\mathrm{NaOH}$