Answer:
Water
Explanation: I think this is the answer if I am wrong please tell me thank you.
Answer: A scientific question can be answered through an investigation. What is tested? Scientists call this an independent variable.
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I think the correct answer from the choices listed above is option A. It is the alveoli that is composed of single layer <span>surrounded by a network of capillaries. These are used to allow oxygen and carbon dioxide to move from the lungs to the bloodstream.</span>
