An ‘Assertion’ and a ‘Reason’ is given below. Choose the correct answer from the following options:
Assertion $\left(\mathrm{A}\right)$: Vinyl halides do not undergo nucleophilic substitution easily.
Reason $\left(\mathrm{R}\right)$: Even though the intermediate carbocation is stabilized by loosely held $\mathrm{\pi }-$ electrons, the cleavage is difficult because of the strong bonding.

• A

  Both $\left(\mathrm{A}\right)$ and $\left(\mathrm{R}\right)$ are correct statements but $\left(\mathrm{R}\right)$ is not the correct explanation of $\left(\mathrm{A}\right).$
• B

  Both $\left(\mathrm{A}\right)$ and $\left(\mathrm{R}\right)$ are wrong statements.
• C

  Both $\left(\mathrm{A}\right)$ and $\left(\mathrm{R}\right)$ are wrong statements and $\left(\mathrm{R}\right)$ is the correct explanation of $\left(\mathrm{A}\right).$
• Correct answer
  D

  $\left(\mathrm{A}\right)$ is a correct statement but $\left(\mathrm{R}\right)$ is a wrong statement.

Hence, the correct answer is option: 'D'.