Detailed Instructions: Given a scientific passage and an answer, generate a question for the given answer.
Q: Passage: A: Homogenized milk is a colloid. The particles in the milk are large enough to seethat's why milk is white instead of clear like water, which is the main component of milk. However, the particles are not large enough to settle out of the mixture. Answer: water
A:
What is the main component of milk?