What best describes a normally open circuit?

A normally open circuit is characterized by its non-conductive state until it is activated, meaning it does not allow current to flow until a specific condition is met, such as a switch being closed. This type of circuit remains open, preventing current from passing through, ensuring that the circuit remains inactive and safe until deliberately engaged.

In contrast, the other options do not accurately depict the nature of a normally open circuit. A circuit in a conductive state before any change refers to closed or normally closed circuits, where current can flow without any further activation. The description of allowing current to flow continuously applies to closed circuits and does not capture the essence of a normally open design. Lastly, while a closed loop with no gaps aptly describes a closed circuit, it fails to represent the operational function of a normally open configuration, which is defined by its default open state.