An optical source is defined as

• A. A single independently mounted light emitting component in a lighting system
• B. A large, multi-beam floodlight
• C. A sensor for detecting ambient light
• D. A generic term for any light source

Answer: (A)

An optical source is the part of a lighting system that actually emits light. It’s typically a single, independently mounted light-emitting component—like an LED module or lamp—that sits inside the fixture. The rest of the system (power supply, wiring, optics, reflectors) shapes and directs that light but doesn’t produce it. So the best description is a discrete emitter within a system. The other options describe either the whole fixture, a sensor, or a vague generic term, none of which identify the emitting element itself.