Some protists<span> are </span>heterotrophs<span>, while others are </span>autotrophs<span>. They cannot be both at the same time.</span>
The blood<span>, which is now low in oxygen, is now collected in veins and travels to the right atrium and into the right ventricle. Now pulmonary circulation starts: The right ventricle pumps </span>blood<span> that carries little oxygen into the pulmonary artery, which branches off into smaller and smaller arteries and capillaries.
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Answer:b)lubricating surfaces
Explanation:took it on edge hope this helped