The correct answer is option 'C' - Direct deflection method.

Explanation:
Bridges are electronic circuits used to measure unknown electrical quantities. However, bridges are prone to leakage current, which can affect the accuracy of the measurements. Leakage current refers to the small current that flows through unintended paths in the bridge circuit. To ensure accurate measurements, it is necessary to remove or minimize this leakage current.

The direct deflection method is a technique used to remove the leakage current from bridges. It involves the use of a sensitive galvanometer or a null detector to detect the presence of leakage current. The galvanometer is connected in parallel to the bridge circuit, and its deflection is observed.

Here is a detailed explanation of the direct deflection method:

1. Set up the bridge circuit: The bridge circuit is set up according to the requirements of the measurement. It typically consists of resistors, capacitors, and/or inductors.

2. Connect the galvanometer: The galvanometer is connected in parallel to the bridge circuit. It is important to ensure that the galvanometer is sensitive enough to detect small currents.

3. Adjust the bridge: The bridge is adjusted by varying the values of the components until the galvanometer shows no deflection. This indicates that the bridge is balanced, and there is no leakage current flowing through the circuit.

4. Measure the unknown quantity: Once the bridge is balanced, the unknown quantity can be measured accurately. The value of the unknown quantity can be determined from the known values of the other components in the bridge circuit.

Advantages of the direct deflection method:
- It is a simple and effective technique for removing leakage current.
- It allows for accurate measurements of unknown electrical quantities.
- It does not require complex calculations or additional equipment.

In conclusion, the direct deflection method is used to remove leakage current from bridges. By connecting a sensitive galvanometer in parallel to the bridge circuit and adjusting the bridge until the galvanometer shows no deflection, accurate measurements of unknown quantities can be obtained.