b
In case of \(N(SiH_3)_3\, N\) atom is \(sp^2\) hybridised, the lone pair is present in \(2p\) orbital and it is transferred to empty \(d\) orbital of \(Si\) forming \(d\pi -p\pi \) bond . Hence nitrogen with \(sp^2\) hybridization has trigonal planar shape.