Which statement correctly defines NO (Normally Open) contacts in circuit logic?

NO (Normally Open) contacts are defined as contacts that are open under normal conditions, meaning that when no control signal is applied, they do not allow current to flow through the circuit. This characteristic is fundamental in various applications, such as in relay systems and control circuits, where the intention is to have the circuit remain inactive until it is intentionally triggered, for instance by a switch or another device.

When the control signal is applied to an NO contact, it closes, allowing current to flow. This behavior is essential for the operation of many automated systems, as it allows for on-demand activation of equipment and eliminates the risk of current flowing unintentionally when the system is in its default state.

In contrast, the other choices present misunderstandings of the functionality or applications of NO contacts, such as implying they are always closed or used exclusively in specific types of circuits, which does not capture their general application in various electrical systems.