1. We need the unit of $\dfrac{E}{H}$, where:

   • $E$ = electric field intensity
   • $H$ = magnetising field

2. Write their SI units:

   • Electric field intensity: $E = \frac{\text{force}}{\text{charge}} = \frac{N}{C} = \frac{V}{m}$ So, unit of $E$ is $V/m$.

   • Magnetising field intensity $H$ has SI unit: $A/m$

3. Therefore, $\frac{E}{H} = \frac{V/m}{A/m} = \frac{V}{A}$

4. But $\frac{V}{A} = \Omega$ which is the unit of resistance, i.e. ohm.

5. Checking options:

   • A: ohm $\checkmark$
   • B: mho $= \Omega^{-1}$ $\times$
   • C: joule $\times$
   • D: newton $\times$

Hence, the correct answer is A: ohm.