Select the one substance that is not a rock.

 - Basalt is not made by living things. It is not a pure substance.
 - Quartzite is not a pure substance. It is a solid.
 - Candle wax is made by humans. It is not a pure substance.
Compare the properties of each substance to the properties of rocks. Select the substance whose properties do not match those of rocks.
Basalt is a rock.
Quartzite is a rock.
Candle wax is made by humans. But rocks are not made by living things.
So, candle wax is not a rock.