I think the circulatory system is the best body system because we need the heart to stay alive, many people live with only one lung. but we need the respiratory system to let oxygen in, and let carbon dioxide out.
Answer:
Estrogen helps control the menstrual cycle and is important for childbearing. Estrogen also has other functions: Keeps cholesterol in control. Protects bone health for both women and men
Explanation:
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