In which of the following transformations is phosphorus pentachloride $(PCl_5)$ used as a reagent?

• A
  $H_2C = CH_2 \rightarrow CH_3CH_2Cl$
• B
  $H_3C - O - CH_3 \rightarrow 2CH_3Cl$
• C
  $CH_3CH_2OH \rightarrow CH_3CH_2Cl$
• D
  $HC \equiv CH \rightarrow CH_2 = CHCl$