The correct answer is: A. Inductance
Inductance is the property of an electric circuit that opposes any change in current through it. This opposition is caused by the buildup of a magnetic field around the conductor as current flows through it. The magnetic field then opposes any change in current, which causes the inductance.
Capacitance is the property of an electric circuit that stores electrical energy in an electric field. This energy is stored when a charge is placed on the capacitor. The charge then creates an electric field between the plates of the capacitor. The electric field stores the energy.
Potential gradient is the rate of change of potential with respect to distance. It is measured in volts per meter. The potential gradient is equal to the electric field divided by the permittivity of free space.
None of the above options are the property of a capacitor which delays any change of voltage across it. The correct answer is inductance.