You forget to include the pair of atoms. But I found similar questions that asks about the following pairs:
H – S
H – Cl
N – H
O – H
C – H
To be able to answer, we must find out the electronegativity of each atom
Electronegativity of H = 2.2
Electronegativity of S = 2.58
Electronegativity of N = 3.04
Electronegativity of Cl = 3.16
Electronegativity of O = 3.5
Electronegativity of C = 2.55
Since all these atoms are paired with H, and they all have electronegativity greater than H, the atom with the highest electronegativity (O) would pair with H to have the greatest electronegativity difference.
The answer is therefore, O – H