Please choose the correct answer to the question: In a container, a mixture of water and salt is stirred so that the salt dissolves completely. Sand is added to this solution and allowed to settle to the bottom of the container. If the container is placed on a heat source and the liquid evaporates completely, what will be left in the container?

Answer1: Nothing will remain in the container. Answer2: Only salt will remain in the container. Answer3: Only sand will remain in the container. Answer4: Salt and sand will both remain in the container.

Answer format: answer1/answer2/answer3/answer4
Answer: answer4