Task: Question Answering
Input (English): Question: A piece of sandpaper was rubbed across a glass table, then the sandpaper was rubbed across some gravel. The friction will be greater between 
 Option1: the sandpaper and the glass table or 
 Option2: the sandpaper and the gravel. 
 Explanation: Rougher surfaces have more friction between them than smoother surfaces.
Output (English): the sandpaper and the gravel.