Two compounds, A and B, have the same molecular formula, C6H8. Both A and B react with two molar equivalents of hydrogen in the presence of platinum to yield cyclohexane. Compound A shows three signals in its broadband decoupled 13C NMR spectrum. Compound B shows only two 13C NMR signals.
Compound A shows an absorption maximum at 256 nm, whereas B shows no absorption maximum at wavelengths longer than 200 nm. What are the structures of A and B?

C&Hs 13C NMR: 3 signals UV:max-256 nm H2 Pt H2 Pt 13C NMR: 2 signals UV: max200 nm