The correct answer is: B. vector
Electric displacement is a vector quantity because it has both magnitude and direction. The magnitude of electric displacement is equal to the product of the electric field strength and the permittivity of the medium. The direction of electric displacement is from the positive charge to the negative charge.
A scalar quantity is a quantity that has only magnitude. For example, temperature is a scalar quantity. It has only magnitude, and no direction.
A vector quantity is a quantity that has both magnitude and direction. For example, velocity is a vector quantity. It has both magnitude, which is the speed, and direction, which is the direction of motion.
In the case of electric displacement, the magnitude is equal to the product of the electric field strength and the permittivity of the medium. The direction of electric displacement is from the positive charge to the negative charge.
Therefore, electric displacement is a vector quantity.