The diagram illustrates the circuit for a hair-dryer. The fan motor is rated at $0.10\,\text{kW}$ and each heater is rated at $0.40\,\text{kW}$. Electricity costs $8.0\,\text{cents/kW h}$. What is the cost of operating the hair-dryer for two hours when switches P and Q are closed and switch R is open?
- A1.6 cents
- B4.0 cents
- C6.4 cents
- D8.0 cents