Option A PH3
Option B (CH3)2
Option C (SiH3)2
Option D (BH3)2
Correct Option D
Solution:
In the given molecules all have completed their octet except (BH3)2. In (BH3)2 boron has 6 valence electrons when it dimerizes which means its octet is incomplete. Hence (BH3)2 is an electron-deficient compound.