Here's how we break it down:

* M: Mass

* L: Length

* T: Time

* I: Electric Current

Let's derive it from the definition of conductivity:

* Conductivity (σ) = Current density (J) / Electric field (E)

Now, let's break down the dimensions of each component:

* Current density (J): Current per unit area, so its dimension is [I/L²] = [I L⁻²]

* Electric field (E): Force per unit charge, so its dimension is [M L T⁻² / I T] = [M L T⁻³ I⁻¹]

Therefore, the dimension of conductivity is:

σ = [J/E] = [I L⁻² / (M L T⁻³ I⁻¹)] = [M⁻¹L⁻³T³I²]