A battery is connected across two parallel conductors (an upper rail and a lower rail). Three identical lightbulbs are arranged between the rails as follows:
• Bulb P is connected directly between the rails.
• Bulb Q is in series with switch S1 between the rails.
• Bulb R is connected between the rails, but switch S2 is wired in parallel with bulb R so that closing S2 provides a direct conducting path between the rails at the same points where bulb R is attached.
Initially both S1 and S2 are open and the circuit has reached steady state. The switches are then closed simultaneously.
Which of the following correctly states which bulbs are lit after both switches are closed?
(a) Only bulb P is lit
(b) All three bulbs are lit
(c) Bulbs P and Q are lit; bulb R is off
(d) Bulbs P and R are lit; bulb Q is off