Electric current is a _ _ _ _ _ _.A. Scalar quantityB. vector quantityC. vector quantity when it is due to the flow of positive charges D. vector quantity when it is due to electrons.

The correct answer is A. Scalar quantity.

Explanation:
Electric Current Definition: Electric current is defined as the rate of flow of electric charge through a conductor. Mathematically, it is given by: Current (I) = Q / t where Q is the electric charge and t is the time.

Nature of Electric Current:

Electric current has a magnitude (the amount of charge flowing per unit time) and a specific direction (the direction of flow of charges or conventional current).
While direction is involved, it does not behave like a vector quantity. A vector quantity must follow vector laws of addition, such as the triangle or parallelogram law of vectors. Electric current does not obey these laws.
Why Electric Current is Scalar:

Electric current is considered a scalar quantity because it adds algebraically when currents meet at a junction, regardless of direction.
Even though it has a direction, this direction does not qualify it as a vector quantity since the vector addition rules are not applicable.
Options C and D:

Electric current is not a vector quantity when it is due to positive charges or electrons. Regardless of the charge carriers, the nature of current remains scalar.
The flow of current depends on the convention, and it is always treated as scalar irrespective of the charge carriers.
Thus, the electric current is a scalar quantity.