<span>Population sizes decrease at higher trophic levels.
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The most common way to get your blood flowing is by exercising, improving your diet, have a hot bath, etc.
The answer would have to be the third option "<span>Clusters and constellations." Clusters is a group of stars that is in a galaxy. Constellations is a line connected by stars to make a picture for example a kite. Galaxy's also include: planets, stars, clusters, comets, and sometimes asteroids.
Hope this helps!
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