Explanation
Correct answer: A.
Choice A is the best answer because it most logically completes the text’s discussion of how kelp forests help marine animals. In this context, "tranquil" means free from disturbance, or calm. The text indicates that ocean currents are powerful and make it difficult for marine animals to hide from predators and that kelp forests slow currents down to create calmer areas. In other words, kelp forests create a more tranquil environment.
Why the other choices are wrong
Choice B
Choice B is incorrect because the text indicates that kelp forests provide shelter for marine animals, meaning they create environments that are safer, not more "dangerous."
Choice C
Choice C is incorrect because the text discusses how kelp forests affect currents in the ocean, and it isn’t clear how an ocean environment could be "imaginative," or full of imagination.
Choice D
Choice D is incorrect because the text indicates that kelp forests create a calm and safe environment, and an environment that is "surprising" would be characterized by unexpected occurrences, not calmness.