Answer: The highest difference is in between N and H thus this will have greatest polarity.
Explanation:More the electro-negativity between any two elements more the polarity in the bond. Electron negativity is the tendency to pull shared pair of electrons towards it self. If the difference between two bonded elements is way too high then it may result in complete transfer of electrons from the less electronegative element to more electronegative one. Thus the bond will be ionic and highly polar.
Among given options,the electro negativity differences are:
A) Al-Si : 1.9-1.61= 0.29
B) S-Cl : 3.16- 2.58 = 0.58
C) N-H : 3.04 - 2.2 = 0.84
D) C-N : 3.04-2.55 = 0.49
The highest difference is in between N and H thus this will have greatest polarity.