rust forming on an iron nail sugar crystals dissolving in water sodium and chlorine forming table salt hydrogen and oxygen reacting to produce water
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: Which of the following is an example of the formation of a mixture?
Possibilities:
- rust forming on an iron nail
- sugar crystals dissolving in water
- sodium and chlorine forming table salt
- hydrogen and oxygen reacting to produce water

sugar crystals dissolving in water