Where does oxygen move from the respiratory system to the circulatory system?

the answer is :In the alveoli

There are millions of alveoli present in the lungs and its capillaries. The oxygen that we inhale, moves from the alveoli to the blood present in the capillaries. During this process, the carbon dioxide that needs to be exhaled out, it moves out from the blood to capillaries and then into the alveoli. So, the exchange or the movement of oxygen takes place in the alveoli.