6. (5 pts) From among the isomeric compounds with molecular formula C4H9Cl, identify the one having a 1H NMR spectrum that: a) contains only a single peak b) has several peaks, including a doublet at d 3.4 c) has several peaks, including a triplet at d 3.5 d) Has several peaks, including two distinct signals, each with an integration of 3H, one of them a triplet at d 1.0 and the other a doublet at d 1.5.