Oxygen-rich blood returns from the lungs to the heart. Which two systems are most directly involved in this process?

A.
digestive and respiratory
B.
respiratory and circulatory
C.
excretory and digestive
D.
circulatory and excretory

1 answer

The correct answer is B. respiratory and circulatory.

The respiratory system is responsible for exchanging gases (oxygen and carbon dioxide) in the lungs, while the circulatory system transports oxygen-rich blood from the lungs to the heart and throughout the body.