The correct answer is: A. capacitive only
Negative voltage regulation is indicative that the load is capacitive only. This is because a capacitor draws current when the voltage across it is increasing, and it releases current when the voltage across it is decreasing. This means that a capacitor will draw current when the output voltage of a regulator is increasing, and it will release current when the output voltage of a regulator is decreasing. This can cause the output voltage of a regulator to drop below the desired level, which is known as negative voltage regulation.
Option B is incorrect because an inductive load will also draw current when the voltage across it is increasing. However, an inductive load will continue to draw current even after the voltage across it has reached its peak value. This means that an inductive load will not cause the output voltage of a regulator to drop below the desired level.
Option C is incorrect because a resistive load will not draw current when the voltage across it is increasing. This means that a resistive load will not cause the output voltage of a regulator to drop below the desired level.
Option D is incorrect because negative voltage regulation is a real phenomenon that can occur in practice.