Which output state corresponds to a target being absent for a Light diffuse Photo Detector?

In the context of a light diffuse photo detector, when a target is absent, the expected output state is OFF. This is because the photo detector is designed to respond to the presence of light that reflects off an object or target. When there is no target to reflect light, the detector does not receive any incoming light, resulting in no signal being generated. Therefore, the output state in the absence of a target correctly corresponds to the OFF condition.

Conversely, when a target is present and light is reflected back to the sensor, the detector would switch to the ON state, indicating a detectable output. The other options, such as variable and transient, refer to situations where the output signal may not be stable, which is not applicable when discussing a target's absence. Thus, OFF is the accurate representation of the detector's state when it detects that no target is present.