If A, B and C are physical quantities, having different dimensions, which of the following combinations can never be a meaningful quantity?
(i) $\frac{\mathrm{AB}}{\mathrm{C}}$
(ii) $\frac{\mathrm{A}+\mathrm{B}}{\mathrm{C}}$
(iii) AB -C²
(iv) (A - B)C