Battery Chargers for Tools, Cell Phones, and Other Electronic Devices

Battery chargers for tools, cell phones, and other electronic devices typically show one signal when charging (e.g., flashing icon, message, red light) and a different signal when charging is complete (e.g., static icon, message, green light) . This system is an application of

A) differential inhibition.
B) conditioned inhibition.
C) backward inhibition.
D) explicitly unpaired.