Answer:
The BEST summary of this paragraph is "Because a tsunami is not one wave, but a series of several waves that can be as far as two hours apart, you must wait several hours after the last wave in order to be sure the tsunami is over."
Explanation:
Option B is the one that best summarizes the given excerpt since it contains all the important information to convey the main idea, besides it does a correct use of paraphrasing and it is direct, functional and coherent, the other three options are lacking one of the points either they are not giving the necessary information or not in the correct way.