Answer:
The correct option is;
d) All of the above
Step-by-step explanation:
a) In an electric circuit through which electric current flows, it is due to the electric charges which can be the negatively charged electrons or the positively charged protons
b) Voltage is the potential difference that results in current flowing through the circuit, therefore, the voltage is applied across the circuit through which current flows
c) The voltage which is the electric potential difference is the change in potential energy in joules of a given system due to the movement of a test charge (in Coulombs) between points in the electric field, ΔE, divided by the value of the test charge, 'q'
V = ΔE/q
Therefore, all of the above are correct.