Task: Question Answering
Input (English): 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  
 (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.
Output (English): D