The figure shows a circuit diagram of a ?Wheatstone Bridge? to measure the resistance G of the galvanometer. The relation \[\frac{P}{Q}=\frac{R}{G}\] will be satisfied only when

• A.                    The galvanometer shows a deflection when switch S is closed
• B.                    The galvanometer shows a deflection when switch S is open
• C.                    The galvanometer shows no change in deflection whether S is open or closed
• D.                    The galvanometer shows no deflection