Hydrocarbons

An unsaturated hydrocarbon \([\mathrm{A}]\) reacts with \(\mathrm{HBr}\) in presence of Benzoyl peroxide to yield [B]
Compound [A] when reacted with cold, dilute alkaline \(\mathrm{KMnO}_4\) gave compound [C], 2-Methylbutane-2, 3-diol But when [A] is reacted with hot \(\mathrm{KMnO}_4\), it yielded \(\mathrm{CH}_3 \mathrm{COOH}\) and a compound [D] Identify compounds [A], [B] and [D]