The correct option is B 5
In NH3, N is bonded to three H atoms and also has a lone pair. Thus, it is sp3 hybridised.
In BF3, B is bonded to three F atoms and has no lone pair. Thus, it is sp2 hybridised.
The hybridisation of NH3 and BF3 are sp3 and sp2 respectively.
Hence, a total of 5 p orbitals are involved in the hybridisation of both the molecules.