Question: Katie has a mixture of iron filings and sand. She wants to separate them. How can she do this?

  Options: 
 A. Shake the mixture, and the iron filings will rise to the surface.
 B. Add water to the mixture, and the sand will dissolve in the water.
 C. Put the mixture through a sieve, and the sand will remain in the sieve.
 D. Pass a magnet over the mixture, and the magnet will attract the iron fillings.
Answer: D