What are the dimensions of electrical resistance?

From Ohm's law, resistance R is given by $\mathrm{R}=\frac{\text{ potential difference }}{\text{ current }}$

$\therefore$ Dimensions of $\mathrm{R}=\frac{{\mathrm{ML}}^2{\mathrm{T}}^{-3}{\mathrm{A}}^{-1}}{\mathrm{A}}={\mathrm{ML}}^2{\mathrm{T}}^{-3}{\mathrm{A}}^{-2}$

Thus, the correct choice is (2).