% Ionic character in the covalent bond $\mathrm{A}-\mathrm{B}$ is:

(Gino that $\left.X_A=2,X_B=3\right)$

% Ionic character in the covalent bond $\mathrm{A}-\mathrm{B}$ is 19.5%.

Ionic character is the proportional difference between the electronegativity of two covalently bound atoms.

% ionic character $=16\left(1\right)+3.5\times 1^2=19.5\mathrm{\%}$

Therefore, option C is correct.