When a tertiary alcohol ${ }^{\prime \prime} A^{\prime}\left(\mathrm{C}_4 \mathrm{H}_{10} \mathrm{O}\right)$ reacts with $20 \% \mathrm{H}_3 \mathrm{PO}_4$ at 358 K , it gives a compound ' $B$ ' $\left(\mathrm{C}_4 \mathrm{H}_8\right)$ as a major product. The IUPAC name of the compound ' $B$ ' is

• A

  but-1-ene
• B

  but-2-ene
• C

  cyclobutan
• Correct answer
  D

  2-methylpropene

Solution

The complete reaction sequence involved is as follows
Thus, the IUPAC name of the product $B$ is 2-methyl propene.

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