The correct option is C >75%
As we know that the hybridization of N in NH3 is sp3, the percent p character must be 3/4×100=75%.
This happens when the structure doesn't have any lone pairs and it is a simple tetrahedral structure. But, here it has a pyramidal shape.
And due to lone pair-bond pair repulsion, the bond angle decreases from an ideal 109.5 degree to 107 degree.
As bond angle decreases, % s character also decreases. But % p character increases. As a result of which here % p will be more than 75% and % s will be less than 25%.