Answer:
A. the digestive, muscular, and respiratory
Explanation:
Muscle weakness affects the muscular system (muscles are in the muscular system) , stomach pain affects the digestive system (stomach is a part of the digestive system), and coughing affects the respiratory system (coughing hinders the ability to breathe properly).
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Your answer is D. untestable and open to change
Answer:
its affected by the number of chromosomes they have