What is the main function of the circulatory system in multicellular organisims. a. to transport materials throughout the body. b. to bring oxygen in the lung
c. to put carbon dioxide into all vessels
d. to expel waste products from the body

The main function of the circulatory system is  a To transport material throughout the body.

Explanation:

Blood in an important component of circulatory system.Blood contain Red blood cell that in turn contain hemoglobin which helps in the transport of oxygen and carbon dioxide to and from various body tissue.

  The circulatory system also helps in the transport of nutrients such as glucose to various parts of our body such as heart,muscle,brain etc.The glucose molecules are utilized by those organs to perform their physiological functions.

    The circulatory system also transport various hormone from the region of secretion to the target cell .

i think that it is plants

a- multicellular

b-eukaryotic

c-no cell wall

d-heterotrophic

e-autotrophic