An alcohol A, when heated with conc. `H_(2)SO_(4)` gives an alkene B. When B is bubbled through bromine water and the product obtained is dehydrohalogenated with exccess of sodamide, a new compound C is obtained. The compound C gives D when treated with warm dilute `H_(2)SO_(4)` in the presence of `HgSO_(4)`. D can also be obtained either byh oxidising A with `KMnO_(4)` or form acetic acid through its calcium salt. Identify A, B, C, and D.