Fact 1: Sharpening an object causes that object to change shape.

Fact 2: Very often their only metal object in the house is a cooking pot or a knife.

Given the two facts above, answer the question "What does sharpening a knife do?" with the following options: 
- change its material
 - make it stay the same
 - lowered energy cost
 - duplicate itself
 - Relieve pain
 - change its shape
 - change its color
 - It gets heated up


 

      change its shape   