Give the decreasing order of basic character at `a,b,c,d` in the following compounds :
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Explanation

(I) `d gt c gt b gt a[(d) 1^@` amine `gt ( c) p-`toluidine gt (b) m-toluidine `gt o-`toluodine]
(II) `d gt b gt c gt a [(d) 2^@` amine `gt (b) 1^@` amine `gt ( c) 3^@` amine `gt (a)` aniline (aromatic amine)
(III) `c gt b gt d gt a [( c) 3^@ (Et_3 ddot N) gt (b) 1^@ (EtNH_2) gt (d) p-`Nitroaniline `gt (a) o-`Nitroaniline].
For `(b)` and `( c)`, refer to Section , under Basic Character of Amines'.
(IV) .