A resistor is connected in series with a battery. The resistance of the resistor is $20\ \Omega$. The potential difference (p.d.) of the battery is $4.0\ \text{V}$. What current flows through the resistor?
- A$0.20\ \text{A}$
- B$4.0\ \text{A}$
- C$5.0\ \text{A}$
- D$80\ \text{A}$