A) 19
NJ2X Notes:
Electromagnetic waves travel at the speed of light which is 299,792,458 meters per second or for the ease of calculation we can round up to 300,000,000 m/s. Frequency and wavelength are related and can be determined by the formulas:
Frequency = Speed of Light / Wavelength
or
Wavelength = Speed of Light / Frequency
The easiest way to deal with this question is to simply memorize the answer