Correct Answer  Option 2 : σ = ρ
1
The correct answer is option 2) i.e. σ = ρ1
CONCEPT:
 The resistivity of a material is defined as the resistance offered by a material of unit crosssectional area and unit length.
It is represented as:
\(\Rightarrow ρ = \frac{RA}{l}\)
Where R is the resistance, l is the length of the material and A is the area of crosssection.
 Resistivity is an intrinsic property i.e. it is the same for a given type of material.

Conductivity (σ) is the reciprocal of electrical resistivity.
EXPLANATION:
Since conductivity is the reciprocal of resistivity, \(σ = \frac{1}{\rho} = \rho^{1}\)