`NH_3` has got pyramidal structure. By replacement of `H` atom it forms `(CH_3)_3 N` and `(SiH_3)_3 N` molecules which are found to have different geometries.
Shape of `(SiH_3)_3 N` with respect to `N` is.
A. Pyramidal
B. T-shaped
C. Trigonal planar
D. Tetrahedral