Answer:
4
Explanation:
The circulatory system includes the blood that has picked up the carbon dioxide from all of the respiring tissues and who also delivered oxygen to them to continue respiring.
The blood will then reach the lung where the carbon dioxide that the tissues released is exchanged for oxygen in the alveoli.
* Blood cells isn't an organ system which makes 1 incorrect.
* Digestive system will in no way bring the blood to the lungs or away from it. This is the circulatory system's job. So 2 is incorrect.
*Lastly, lungs are organs and the question asks for organ systems. So 3 is incorrect.
We've had the same amount of water on our planet since the beginning of time. Even though 70 percent of the globe is covered in water, less than 1 percent is accessible to us.
But now there is 6.7 billion people using that water. We're on track to be up to 8 billion people in 15 years. With our current population, there is already water stress.
Our bodies change food into energy.
