A

Step 1: Understand the variables involved.
In a capacitor, when two plates are charged with equal and opposite charges Q, the electric field created between them can lead to a phenomenon known as leakage current when a dielectric material is used.
Step 2: Identify the relevant parameters.
The leakage current depends on the dielectric constant (K), the permittivity of free space ($\\epsilon_{0}$), and the resistivity (ρ) of the dielectric material.
Step 3: Derive the relationship for leakage current.
The leakage current (i) can be expressed in terms of these parameters. The relationship is given by
$$i = \frac{Q}{K \epsilon_{0} \rho}$$
where:
- $Q$ is the charge on each plate,
- $K$ is the dielectric constant of the material,
- $\epsilon_{0}$ is the permittivity of free space, and
- $\rho$ is the resistivity of the dielectric.
Step 4: Conclusion.
This equation shows how the leakage current decreases with increasing dielectric constant and resistivity. Hence, it is established that the leakage current due to the dielectric is given by the specified relationship.