You are presented with the question "what allows molecules to travel to control many cell activities" and the following answer choices: 
- skin
 - heat energy
 - animal transport
 - bloodstream
 - Chemical energy
 - nasal passage
 - movement
 - fat tissue

Now knowing that hormones control many cell activities, so they are very important for homeostasis and hormones travel in the bloodstream to cells that are called target cells a, choose the best answer.


 

    bloodstream     