Maxwell’s displacement current is

The correct option is due to changing electric field.

Maxwell’s displacement current arises in regions of space where the electric field (and hence the electric flux) is changing with time, even in the absence of any real flow of electric charges (such as in a vacuum or between the plates of a charging capacitor).

To resolve the inconsistency in Ampere's Circuital Law for non-steady currents (like a capacitor being charged), James Clerk Maxwell postulated that a changing electric field produces a magnetic field in the same way as a conduction current does. He defined this effect in terms of a virtual current called the displacement current, $I_d$.

The mathematical expression for the displacement current is given by:

$$I_d={\epsilon }_0\frac{d{\Phi }_E}{dt}$$

where:
• ${\epsilon }_0$ is the permittivity of free space,
• ${\Phi }_E$ is the electric flux linked with the region.

Since the electric flux ${\Phi }_E$ is directly proportional to the electric field $E$, the rate of change of electric flux $\frac{d{\Phi }_E}{dt}$ represents a changing electric field. Therefore, displacement current is fundamentally due to a changing electric field.