20. which is the circuit used when finding thevenin resistance in a bridge circuit?

Brief Explanations:

To find Thevenin resistance in a circuit, we first remove the load - related components. Then we replace voltage sources with short - circuits and current sources with open - circuits. In the case of a bridge circuit, we simplify the circuit by these means. The circuit that represents the Thevenin resistance has no load, voltage sources are short - circuited, and current sources are open - circuited. Among the given options, the correct one is the circuit where voltage sources are short - circuited and the load is removed.

Answer:

C. The circuit with voltage sources short - circuited and load removed.