For a science experiment, John gradually added a sodium hydroxide (NaOH) solution to warm vegetable oil in a glass test tube. He observed that combining the two clear liquids resulted in a solution that turned cloudy. Which statement best explains why the solution became cloudy?

The best statement that explains why the solution became cloudy when John added sodium hydroxide solution to warm vegetable oil is:

**D. The sodium hydroxide solution and vegetable oil underwent a chemical change.**

Cloudiness often indicates the formation of an emulsion or other reaction products when two substances that normally do not mix well (like oil and water) are combined, suggesting that a chemical interaction has occurred. In this case, sodium hydroxide may be reacting with components in the vegetable oil, leading to the formation of products that are not soluble in the original liquid mixture, thereby causing the observed cloudiness.