What type of current constantly changes direction of flow and magnitude?

The type of current that constantly changes direction of flow and magnitude is alternating current (AC). AC is characterized by its oscillating nature, where the current reverses its direction periodically. This is typically illustrated by a sinusoidal waveform. Unlike direct current (DC), which flows steadily in one direction and maintains a constant magnitude, AC's ability to change direction and magnitude allows it to be efficiently transmitted over long distances. This property is crucial for the functionality of our electrical grid, as it enables the use of transformers to step up or step down voltage levels, ensuring that electricity can be delivered effectively to homes and businesses.

In contrast, static refers to a stationary charge, and inertial relates to mass and motion; neither of these concepts involves current flow or changes in direction and magnitude. Therefore, AC is the correct answer as it encompasses the behavior described in the question.