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]

1. A [A] 2-Methylbut-2-ene
   [B] 2-Bromo-3-methylbutane
   [D] Propanone
2. B [A] Pent-2-ene
   [B] 2-Bromopentane
   [D] Propanal
3. C [A] Pent-1-ene
   [B] 1-Bromopentane
   [D] Propanoic acid
4. D [A] 3-Methylbut-1-ene
   [B] 1-Bromo-3-methylbutane
   [D] Propanoic acid.