Which force keeps the planets in their orbits around the Sun?
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OPTIONS:
- gravity
- magnetism
- electricity
- friction

gravity

Beaver dams can cause floods. This statement shows how
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OPTIONS:
- animal growth is affected by environmental conditions
- animal behavior may affect the environment
- an animal's health depends on its environment
- an animal's development depends on its environment

animal behavior may affect the environment

Which BEST explains why green marine algae are most often restricted to the top 100 meters of the ocean?
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OPTIONS:
- They have no roots to anchor them to the ocean floor.
- They can live only where there is light.
- The pressure is too great for them to survive below 100 meters.
- If the algae lived below 100 meters they would be eaten by animals.
They can live only where there is light.