Question: Which BEST explains why green marine algae are most often restricted to the top 100 meters of the ocean?

  Options: 
 A. They have no roots to anchor them to the ocean floor.
 B. They can live only where there is light.
 C. The pressure is too great for them to survive below 100 meters.
 D. If the algae lived below 100 meters they would be eaten by animals.
Answer: B