The 1H NMR spectrum of melatonin, the chapter-opening molecule, is more complex than other...

The 1H NMR spectrum of melatonin, the chapter-opening molecule, is more complex than other examples we have encountered, but the chemical shift and splitting patterns observed for several peaks can be explained by what we have learned about 1H NMR thus far. (a) Which protons in melatonin give rise to signals [A]–[D]? (b) Explain the splitting pattern observed in signal [C].