AI-generated practice question — model-generated for extra practice, not a previous-year CBSE board question.
(C) Ω m
The SI unit of electrical resistivity is ohm-metre (Ω m), from the relation $R = \rho \dfrac{l}{A}$, giving $\rho = \dfrac{RA}{l}$ → Ω × m² / m = Ω m.
Source: Chapter 11, Section 11.5
From $R = \rho \frac{l}{A}$, rearranging gives $\rho = \frac{RA}{l}$. Units: $\frac{\Omega \cdot m^2}{m} = \Omega\ m$. The textbook explicitly states "The SI unit of resistivity is Ω m." Don't confuse resistance (Ω) with resistivity (Ω m).