Question

the respiratory system works in conjunction with the ______ system to deliver oxygen to the cells of the body.
a digestive
b endocrine
c nervous
d cardiovascular

Explanation:

The respiratory system takes in oxygen from the air. The cardiovascular system, which includes the heart and blood - vessels, then transports this oxygen - rich blood to the cells of the body. The other systems listed (digestive, endocrine, nervous) are not primarily involved in oxygen delivery to cells in conjunction with the respiratory system.

Answer:

D. cardiovascular