SI unit of the quantity electric current is?
A. Volt
B. Ampere
C. Candela
D. Newton

Hint:We know electric current is defined as the rate of flow charge. If we have one Coulomb of charge and it moves under the potential difference from one end of the conductor to the other in one second, then the current constituted will be defined as the standard SI unit of current. The direction of electrons is taken to be opposite the direction of electric current.

Complete answer:
Electrons are minute particles that exist within the molecular structure of a substance. Sometimes, these electrons are tightly held, and the other times they are loosely held. When electrons are loosely held by the nucleus, they are able to travel freely within the limits of the body. Electrons are negatively charged particles hence when they move a number of charges moves and we call this movement of electrons as electric current.

It should be noted that the number of electrons that are able to move governs the ability of a particular substance to conduct electricity. Some materials allow current to move better than others. Based on the ability of the material to conduct electricity, materials are classified into conductors and insulators.The electric current is measured in units of Ampere denoted by A. ampere is one amongst the seven-fundamental quantities in the dimensional analysis system.

So, the correct option is B.

Note: The four options given in the question are closely related. The volt is the unit of measurement of the potential difference. The movement of electric charge from one end of the conductor to the other cannot take place on its own and to facilitate such movement potential difference is required. The potential difference led to the electric field, and we know that a charge placed in an external electric field experiences a force and due to this force, the charge moves from one end of the conductor to the other and constitutes electric current.