Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: The human eye can distinguish only red, green, and blue light. These three colors are the primary colors of light. All other colors of light can be created by combining the primary colors. Secondary colors of lightcyan, yellow, and magentaform when two primary colors combine equally. Answer: red, green, blue
Output:
What three primary colors of light can be distinguished by the human eye?