You are presented with the question "What force causes an object to change shape?" and the following answer choices: 
- quadriceps
 - Electrical energy
 - mechanical
 - Heat energy
 - friction
 - compressional
 - flow of electrons
 - kinetic energy

Now knowing that folding an object causes that object to change shape and folds are usually caused by compressional forces, choose the best answer.


 

      compressional   