The correct answer is: A. Magnitude and direction of current remains constant.
Direct current (DC) is an electric current that flows in one direction only. It is produced by batteries, generators, and solar cells. DC is used in many applications, such as power supplies, electronics, and telecommunications.
The magnitude of a current is the amount of charge that flows through a conductor per unit time. The direction of a current is the direction in which the charge flows. In the case of DC, the magnitude and direction of the current remain constant.
Option B is incorrect because the magnitude and direction of current do not change with time in the case of DC.
Option C is incorrect because the magnitude of current does not change with time in the case of DC.
Option D is incorrect because the direction of current does not change with time in the case of DC.