The correct answer is D) 7. A light-emitting diode (LED) is a type of solid-state semiconductor device that emits light when an electric current passes through it. In the illustration EL-0068, the device labeled 7 is the light-emitting diode, as it is the only option that matches the physical characteristics and function of an LED. The other answer choices, 1, 2, and 4, are likely other types of semiconductor devices, such as transistors or integrated circuits, which do not emit light as their primary function.