Which of the following circuits can hold a binary state indefinitely until switched?

The bistable multivibrator is a type of flip-flop circuit that can maintain one of two stable states indefinitely until it receives an input to switch to the other state. This characteristic allows it to serve as a memory element, where it can store binary information (0 or 1). The circuit has two stable states, and external inputs can trigger state changes, but once set, it will remain in that state until actively changed.

In contrast, the monostable multivibrator has a single stable state and will return to this state after a defined duration when triggered. It cannot hold a state indefinitely without a continuous input signal. The astable multivibrator continuously oscillates between two states and does not hold either state, thus it does not maintain a binary state. A resistor-capacitor circuit is typically used for timing applications and does not inherently maintain a binary state; rather, it would discharge and change its voltage over time.

Therefore, the distinction lies in the capability of the bistable multivibrator to maintain a stable state indefinitely, which is the primary reason it is the correct choice in this scenario.