In order to grow your cells need to expand and divide in order for your body to grow.
Answer:
a. concentration gradient
Explanation:
i did it in apex and got it right.
My best guest is probably C or A.
Most coelomates possess a "A. Circulatory system" because the main feature of these animals is that they posses a digestive tract, which requires a certain amount of circulation.
see if you can find clues is all i know to tell you