Which of the following body systems is the least directly responsible for the action described below? Carbon dioxide from cellular respiration is removed from cells and exhaled.

-circulatory
-muscular
-respiratory
-endocrine

In science class maria observed a white color and cut flowers she sees that the petals turn red when the flowers sitting in a vase that has red colored water she forms a hypothesis that the color reaches the flower through the stem what should we do to confirm the hypothesis