Current is the rate of flow of electrons per unit time and is measured in amperes (A). A coulomb (C) is the quantity of electricity conveyed in one second by a current of one ampere.
In electrical wiring, which of the following are proportional?
the diameter of the wire and the amount of the voltage 

the length of the wire and the amount of the voltage 

the length of the wire and the amount of the current 

the diameter of the wire and the amount of the current 