Concept:Basicity is inversely related to
pKb​: the weaker the base, the higher its
pKb​ value.
Explanation:Aliphatic amines are stronger bases than arylamines.
In arylamines, the lone pair on nitrogen is delocalised into the benzene ring, making it less available for protonation.
Hence, arylamines are the weakest bases among the given options.
Since a weaker base has a higher
pKb​, arylamine shows the highest
pKb​ value.
Answer:A. Arylamine