Explanation:

- Coulomb per second is a unit of electric current. It measures the rate of charge flow in a circuit.

- Option 1: Ohm

- Ohm is a unit of electrical resistance, not current.

- Option 2: Volt

- Volt measures electric potential difference. It is not related to charge flow per second.

- Option 3: Ampere

- Ampere is the unit of electric current. It is indeed defined as one coulomb per second.

- Option 4: Joule

- Joule is a unit of energy, not relevant to the flow of charge.

Option:3 - Ampere is the correct answer.