You will be given a definition of a task first, then some input of the task.
Given a scientific passage and an answer, generate a question for the given answer.

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