In the circuit the galvanometer $G$ shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor $R$ will be

Question

 

$\begin {array} {1 1} (A)\;200\Omega & \quad (B)\;100\Omega \\ (C)\;500\Omega & \quad (D)\;1000\Omega \end {array}$