An example of memory logic by a control relay is __________.

A seal-in circuit, also known as a holding circuit, is an excellent example of memory logic as implemented by a control relay. This type of circuit maintains the state of a relay or contactor after it has been initially energized, allowing the device to continue operating even if the activation signal is removed. Essentially, when the control relay is energized, it closes its own contacts which provides a continuous path for current, thus "remembering" its on state. This functionality is crucial in control systems, where consistent operation is needed without constant intervention.

The other options may involve aspects of control and operation, but they do not inherently demonstrate the concept of memory logic as effectively as a seal-in circuit does. Bypass logic typically refers to a method that allows a control system to function while bypassing certain components, which does not involve memory retention of state. Manual override is a means of allowing human intervention to control a system directly, but does not imply a retention of state once the manual control is removed. Therefore, the seal-in circuit is the most definitive example of memory logic in this context.