Select the one substance that is not a rock.

 - Conglomerate is not made by living things. It is not a pure substance.
 - A computer processor is made in a factory. It is a solid.
 - Marble is not made by living things. 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.
A computer processor is made in a factory. But all rocks are formed in nature.
So, a computer processor is not a rock.
Marble is a rock.
Conglomerate is a rock.