What are the similarities between cardiovascular and respiratory systems? Check all that apply A: Both systems need a healthy oxygen supply to sustain human life.
B: Both systems use high amounts of carbon dioxide in the blood stream.
C: Both systems use circulation as the primary source of transporting blood throughout the body.

i believe the answer is A and C

Explanation:

both systems work together to circulate blood and oxegyn around the body.  both need a healthy amount of oxegyn to sustain human life and use circulation as the primary source of transporting blood throughtout the body.

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