You are presented with the question "Cells are organized into tissues to what?" and the following answer choices: 
- Veins and arteries.
 - allow growth
 - move blood
 - become functional units
 - by keeping them warm
 - organize hair
 - protect plants
 - change body color

Now knowing that cells are organized into tissues, and tissues form organs and different tissues are in turn grouped together to form functional units, called organs, choose the best answer.


 

    become functional units     