A tertiary alcohol H upon acid catalyzed dehydration gives a product I. Ozonolysis of I leads to compounds J and K. Compound J upon reaction with KOH gives benzyl alcohol and a compound L, whereas K on reaction with KOH gives only
Compound H is formed by the reaction of
The best approach is to go through each and every option and see if the product on dehydration gives I; Try continuing the sequence until you get M. The option that is consistent through each step of the way is the correct one!
The product above is I. Fron now now, we just have to follow the sequence: