Answer:D, a magnet
Explanation: mixtures are made up of two or more substances that are not chemically combined. When mixed, the identities of the original substances stay the same.
Since they are only physically combined, a mixture can be separated into its original substances by using the substances' characteristic properties.
For example, since iron is magnetic and sand is not magnetic, if a magnet is held over a dish containing a mixture of sand and iron filings, the iron filings would be attracted to the magnet, and pure sand would be left behind.