Question: Identify A and B, isomers of molecular formula \({{\bf{C}}_{\bf{3}}}{{\bf{H}}_{\bf{4}}}{\bf{C}}{{\bf{l}}_{\bf{2}}}\), from the given \({}^{\bf{1}}{\bf{H}}\)NMR data: Compound A exhibits signals at 1.75 (doublet, 3H,\({\bf{J = 6}}{\bf{.9 Hz}}\)) and 5.89 (quartet, \({}^{\bf{1}}{\bf{H}}\),\({\bf{J = 6}}{\bf{.9 Hz}}\)) ppm. Compound B exhibits signals at 4.16 (singlet, 2 H), 5.42 (doublet, \({}^{\bf{1}}{\bf{H}}\),\({\bf{J = 1}}{\bf{.9 Hz}}\)), and 5.59 (doublet, \({}^{\bf{1}}{\bf{H}}\), \({\bf{J = 1}}{\bf{.9 Hz}}\)) ppm.