How do you guys say to the cashier in the gas station that you want to fill out the car gallon? *tank*? with is not a subject but idk how to say so someone !

Two students are discussing the flow of electricity. student a says that voltage is a measure of the amount of electron flow in a circuit. student b says that power is the product of voltage and current. which of the following statements is correct? a. only student a is correct b. only student b is correct c. both of the two students are correct d. neither of the two students is correct