Which one amongst the following possesses an sp hybridized carbon in its structure

• A

  ${\mathrm{CH}}_2=\mathrm{C}\cdot \mathrm{Cl}-\mathrm{CH}={\mathrm{CH}}_2$

• B

  ${\mathrm{C}.\mathrm{Cl}}_2={\mathrm{C}.\mathrm{Cl}}_2$

• C

  ${\mathrm{CH}}_2=\mathrm{C}={\mathrm{CH}}_2$

• D

  ${\mathrm{CH}}_2=\mathrm{CH}-\mathrm{CH}={\mathrm{CH}}_2$