The correct option is D In pyridine, lone pair of nitrogen is delocalised
Pyridine, is much less basic than typical aliphatic amines, but for a very different reason: the unshared pair is in an sp2 , which is much lower in energy than the electron pair of aliphatic amines, which is in an sp3 . Therefore, pyridine is less easily protonated than typical aliphatic amines such as triethylamine .