Which of the following circuits allows for the automatic restart of a machine after a stop command?

The correct answer is the continuous-cycle circuit. This type of circuit is specifically designed to allow a machine to automatically restart after being stopped. Continuous-cycle circuits facilitate operations where ongoing functionality is necessary, often found in processes that require consistent or recurrent activation without the need for manual restart after a stop command.

This design is crucial in various industrial applications where downtime needs to be minimized and efficiency maximized, as it can automatically resume operations based on sensor input or pre-programmed conditions. The continuous nature of these circuits means they are ideal for processes where maintaining flow is critical.

In contrast, the other options are not structured to facilitate an automatic restart after a stop command. Such circuits may serve different functions but lack the essential feature of automatic resumption inherent in continuous-cycle circuits. Understanding the function and design of these circuits helps in selecting the appropriate one for specific operational requirements in maintenance practices.