Bond angle in `PH_3` si closer to `90^(@)` while that in `NH_3` is `104.5^(@)`. Which of the following best explains this structural feature?

Options

A. Due to larger size of the lone pair electron cloud, there is larger lone pair - bond pair repulsion in `PH_3` compared to `NH_3`
B. Higher electronegativity of nitrogen concentrates the bond pair electron cloud near the central atom which increases the bond pair - bond pair repulsion which in turn decreases the bond angle in `NH_3`
C. Energy difference between 3s an,d 3p orbitals is quite high and hence the lone pair on phosphorous prefers to occupy unhybridized s- orbital rather than hybridized `sp^3` hydridized orbital which causes its s-orbital energy to increase.
D. Phosphorous forms `ppi-dpi` bonds while nitrogen does not.

Answer

C