Which system has the highest frequency?

Electro-Optics operates at significantly higher frequencies compared to RADAR, radio, and television systems. This technology relies on the interaction of light (which is part of the electromagnetic spectrum) with electronic systems. The frequency of light can range from about 400 terahertz (THz) for visible light to several petahertz (PHz) for ultraviolet light, placing it at the extreme high end of the electromagnetic spectrum.

In contrast, RADAR operates in the microwave range, typically between 1 GHz to 40 GHz. Radio broadcasts generally operate in the kilohertz (kHz) to megahertz (MHz) range, while television signals are transmitted at frequencies between about 50 MHz to 1 GHz. Therefore, in terms of frequency, Electro-Optics stands out as utilizing far higher frequencies than the other listed technologies, making it the correct choice.