Toxins are removed from the bloodstream by the liver. The stomach signals for the production of gastric juices. Food molecules are transported to the organs of the body. Gases are exchanged between the lungs and blood vessels.
I gave my students this multiple choice question: Which statement best describes how the circulatory system and respiratory system can work together?

Only one answer is correct among these 4 choices:
- Toxins are removed from the bloodstream by the liver.
- The stomach signals for the production of gastric juices.
- Food molecules are transported to the organs of the body.
- Gases are exchanged between the lungs and blood vessels.

Could you tell me which one is correct?

Gases are exchanged between the lungs and blood vessels.