You are given a short paragraph, a question and two choices to answer from. Choose the correct answer based on the paragraph and write the answer(not the key).
Q: Paragraph: Rougher surfaces have more friction between them than smoother surfaces.
 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 
 Choices: A)the sandpaper and the glass table or 
B)the sandpaper and the gravel.
A:
the sandpaper and the gravel.