Which among the following halide/s will not show S _ N 1 reaction:

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 ${S}_{N}1$ reaction, due to very
less stability of carbocation formed and partial
double bond character in C — Cl bond.

Since ${CH}_{3} - CH = \overset{+}{C}H$ is very unstable, ${CH}_{3} - CH =$ $CH - Cl$ cannot give ${S}_{N}1$ reaction.

Hence, the answer is B.