Define resistivity of a material and give unit ?

Question

$\begin{array}{1 1} (a)\;\rho=RAL;ohm\\ (b)\;\rho=\frac{RA}{L};ohm\;meter \\ (c)\;\rho=\frac{RA}{L^2};ohm \\ (d)\;\rho=\frac{RL}{A};ohm/m \end{array} $