The load in a control circuit is energized when which condition is met?

In a control circuit, the load is energized when any one of the switches is closed. This means that the circuit is designed in such a way that the action of closing just one switch allows current to flow through the load, activating it.

This type of configuration is often used for convenience in applications such as lighting systems or other control systems, where multiple switch locations are desired for ease of access or control. For example, in a three-way switch setup, activating any one of the switches allows you to control the load, illustrating the functionality of the circuit that permits activation through just a single point of control.

The other conditions would not effectively energize the load; for instance, if all switches are closed, it might imply a different wiring scenario depending on how they are configured, while having no switches closed clearly means the circuit is open and cannot allow current to flow. Additionally, requiring at least two switches to be closed would restrict access and functionality, which isn't typical for most standard control circuit designs.