Answer;
-Circulatory system
The respiratory system works with the circulatory system to add oxygen to the blood and remove carbon dioxide from the body.
Step-by-step explanation;
-The circulatory system is the body's transport system. It is made up of a group of organs that transport blood throughout the body. The heart pumps the blood and the arteries and veins transport it. Oxygen-rich blood leaves the left side of the heart and enters the biggest artery, called the aorta.
-The circulatory and respiratory systems work together to provide body cells with oxygen which is essential for cellular respiration. This process involves the breaking down of glucose so that energy is released in a form that cells can then use. During cellular respiration, carbon dioxide is produced as a waste product. The carbon dioxide then needs to be removed from the cells or it would cause damage or death to them.