Question: A student has a mineral sample. He wonders if the sample is the mineral mica. He knows the cleavage pattern of mica is a smooth, flat sheet. The student can best find out the cleavage pattern of the sample by

  Options: 
 A. shining a light on the mineral.
 B. soaking the mineral in water.
 C. rubbing a penny against the mineral.
 D. breaking off a piece of the mineral.
Answer: D