The correct answer is: B. an increase in applied voltage makes a capacitor charge.
A capacitor is a device that stores electrical energy in an electric field. It consists of two conductive plates separated by an insulating material, called a dielectric. When a voltage is applied to the capacitor, the electrons on one plate are attracted to the positive terminal of the voltage source, while the electrons on the other plate are attracted to the negative terminal. This creates an electric field between the plates, which stores the electrical energy.
If the voltage applied to the capacitor is increased, the electric field between the plates will also increase. This will cause more electrons to be attracted to the plates, and the capacitor will charge. Conversely, if the voltage applied to the capacitor is decreased, the electric field between the plates will also decrease. This will cause fewer electrons to be attracted to the plates, and the capacitor will discharge.
Options A and C are incorrect because a steady value of applied voltage will not cause the capacitor to charge or discharge. Option D is incorrect because it does not include all of the possible outcomes.