Answer: Option (C) is the correct answer.
Explanation:
Atoms which have high difference in electronegativity will be more polar in nature.
This is because more electronegative atom will attract the electrons more towards itself. And, this causes development of a partial negative charge on the electronrgative and a partial positive charge will develop on the atom from which electrons have been withdrawn.
For example, N-H will be polar in nature because of the difference in electronegativity of N and H.
Whereas Al-Si, S-Cl, and C-N are all non-metals with not much difference in electronegativity.
Thus, we can conclude that N-H pair of atoms has the greatest polarity.