Although it is not given here, I was able to find the complete question. In the question, we are provided that the photodetectors respond to a wavelength between 400 and 1700 nm. Next, we are asked which of the options will be detected by the detectors.
In order to work this out, we use the following equations to convert the options in terms of wavelength:
λ = c/v; when the frequency v is given
and
λ = hc/E; when the energy E is given
Using the equations, we can see that the laser with v = 4.35 x 10¹⁴ s⁻¹ will be detected because:
λ = 3 x 10⁸ / 4.35 x 10¹⁴ = 690 nm, which is within our required range
