Which types of relays change state immediately when the initiating contact is closed?

The correct choice, referring to one-shot and interval relays, is grounded in the fundamental operation of these relay types.

One-shot relays are designed to change their state immediately when an initiating contact is closed. This function is ideal for applications where a single action is required from the relay upon receiving a trigger, such as activating a device or circuit just once. This immediate response makes them essential for scenarios requiring a quick reaction without delay.

Interval relays also change their state immediately upon the initiating contact being closed; however, they are unique in that they maintain their state for a specified duration before returning to the original state. This means that while they respond immediately upon activation, they are typically associated with a timed function once activated.

In contrast, on-delay relays and recycle relays introduce a time element before changing state. On-delay relays take a predetermined amount of time before they switch after receiving a signal, whereas recycle relays switch back and forth upon receiving an initial signal and require additional actions to change state. Off-delay relays change state after a delay once the initiating signal is removed, indicating a time-based operation that differs from the immediate response characterized by the one-shot and interval relays.

Thus, emphasizing the immediate response upon contact