What type of current maintains a constant polarity?

The type of current that maintains a constant polarity is Direct Current (DC). DC is characterized by the flow of electric charge in a single direction, which results in a steady voltage and current level over time. This consistent polarity makes it suitable for applications that require stable and constant power, such as battery-operated devices.

In contrast, Alternate Current (AC) changes its direction periodically, which means that its polarity shifts back and forth. This feature allows AC to be more efficient for long-distance power transmission but does not provide the same consistent current as DC.

Pulsed Current varies in its output, often alternating between on and off states, but it does not maintain a constant polarity like DC. Static Current is not a standard term used to describe electrical currents in practice but might refer to the charge in a stationary state, which does not involve the flow of current.

Thus, the clarity and stability provided by Direct Current make it the correct answer when considering the question of which type of current maintains a constant polarity.