Question: When Linda needed to sharpen her knife, she did it by rubbing her knife over two different surfaces. She tried the whetstone and noticed that it was bumpier than the chunk of rubber. She realizes that the sharpening surface that gets hotter to the touch when a knife is rubbed against it is the (A) whetstone (B) chunk of rubber  Do not use A and B to answer the question but instead, choose between "whetstone" and  "chunk of rubber".
Answer:
whetstone