The electromagnetic spectrum of visible light lies in the ___________ frequency range of the spectrum.

1 GHz (10^9 Hz) corresponds to the microwave frequency range, which is roughly six orders of magnitude below visible light.

100 GHz falls in the millimeter-wave or far-infrared region of the spectrum, still well below the frequency of visible light.

10 THz is in the terahertz or far-infrared range, just below the infrared-to-visible boundary and not within the visible spectrum.

Visible light spans roughly 430 THz to 770 THz, which equates to 0.43 to 0.77 petahertz (PHz). Among the choices given, 1 PHz (10^15 Hz) is the only value that falls within the correct order of magnitude for the visible portion of the electromagnetic spectrum. The other options are either far below (GHz/THz range) or above (100 PHz, which enters X-ray territory) the visible band.

100 PHz (10^17 Hz) is in the ultraviolet-to-soft-X-ray range, which is above the visible light spectrum.