Amines Part 1

In phenyl methanamine, the lone pair on nitrogen of $-{\mathit{N}\mathit{H}}_2$ group is localised and does not undergoes resonance as attached to $\mathit{s}{\mathit{p}}^3$-hybridised C-atom.
Phenyl methanamine or benzyl amine$\left(\mathit{B}\right),\left(\mathit{C}\right)$ and $\left(\mathit{D}\right)$ are aromatic amines in which lone pair of electrons of N-atoms goes in resonance
(+ $\mathit{R}$ effect) with the benzene ring. So, Lewis basicity or donation of lone of electrons of these amines will be decreased in comparison to (A).$+\mathit{I}$ effects of two $-{\mathit{C}\mathit{H}}_3$ groups are in compensation with $-\mathit{R}$ effect of the ring.$+$ l effect of one $-{\mathit{C}\mathit{H}}_3$ group is trying to compensate $-\mathit{R}$ effect of the ring.It has no $+$ leffect on $\mathit{N}$-atom to outweigh $-\mathit{R}$-effect of the ring.
So, $\mathit{A}$ is purely aliphatic $1^{\circ }$-amine. $\mathit{B}$ is aromatic $3^{\circ }$-amine with more aliphatic nature (for two $-{\mathit{C}\mathit{H}}_3$ groups). $\mathit{C}$ is aromatic $2^{\circ }$-amine with less aliphatic nature (for one $-{\mathit{C}\mathit{H}}_3$ group).
$\mathit{D}$ is purely aromatic $1^{\circ }$-amine. Hence basicity order is $\mathit{A}>\mathit{B}>\mathit{C}>\mathit{D}$.