You are presented with the question "Kidneys are a part of what system?" and the following answer choices: 
- allow growth
 - excretory
 - respiratory
 - organ
 - complex
 - storing water
 - endocrine
 - circulatory

Now knowing that organs of excretion make up the excretory system and excretion begins with the kidneys, choose the best answer.


 

  excretory       