Which of the following lamp types emits an almost monochromatic yellow light and provides the...

Low-pressure sodium (LPS) lamps emit a nearly monochromatic yellow light, which severely limits color rendition. This makes them unsuitable for CCTV surveillance where accurate color reproduction is needed. They are, however, energy efficient and used in some outdoor lighting applications where color accuracy is not critical.

B (Incandescent), C (Fluorescent), and D (Metal halide) all offer better color rendition than LPS lamps, with metal halide being the best for color fidelity.