You are presented with the question "What occurs when muscle fibers get longer?" and the following answer choices: 
- photosynthesis
 - rapid expansion
 - kinetic energy
 - cramps
 - relaxation
 - fertilization
 - movement
 - sweating

Now knowing that muscle contraction occurs when muscle fibers get shorter and muscles can only contract and relax, choose the best answer.


 

     relaxation    