Answer:
excretory system and circulatory system
Explanation:
Options for the question are
urinary system
nervous system
excretory system
circulatory system
Solution
Blood is part of circulatory system and as it move through various organs it exchanges the gases i.e give oxygen to the cell and take carbon dioxide from them. After taking CO2, the blood becomes impure and hence it passes through the kidney before going to the heart. Kidney is part of excretory system which removes carbon dioxide from blood and thus purifies it.
Hence, correct answer is excretory system and circulatory system
