Read the following paragraph and answer the question. Give ONLY the answer, no other words or explanation.

For example:

Answer: <most likely answer, as short as possible>.

Paragraph: 
wavelength : The distance between two crests of a wave of light. The color of light is related to its wavelength. This is inversely proportional to frequency.


Question: The distance between two crests of a wave of light is referred to as what, which is related to the color of light?
wavelength
Wavelength.