Spectrum B:
Two DBEs. The 1H singlet at 9.5 and the 13C peak at 207 ppm strongly indicate an aldehyde with no alpha proton. The three signals in the 5-6 ppm range, in combination with the 13C peaks at 118 and 134 ppm, suggest a monosubstituted alkene. What do we have left over? A CH3 singlet that integrates to 6H, indicating C–C(CH3)2-C or similar, and also a CH2 doublet that is split by a neighboring alkene C-H.