Vinylic halides are organic compounds containing their halogen atom bonded to one of the two carbon atoms in the double bond present in that molecule.
Vinyl halide will not show SN1 reaction, due to very
less stability of carbocation formed and partial
double bond character in C — Cl bond.
Since CH3−CH=C+H is very unstable, CH3−CH= CH−Cl cannot give SN1 reaction.
Hence, the answer is B.

