Which is a concluding sentence from the paragraphs of this passage? A) The poor water circulation inside most blue holes makes them anoxic. B) The Great Blue Hole is now one of the country’s top tourist attractions. C) The Great Blue Hole is the result of repeated collapses of an underwater cave system during the Ice Age. D) The Seven Natural Wonders of the World include incredible places like Mount Everest, the Grand Canyon, and the Great Barrier Reef.

To determine the concluding sentence from the given options, we need to identify the sentence that best summarizes or encapsulates the primary theme or brings a logical closure to the information presented in the passage. While I do not have the entire passage to refer to, we can still analyze the options provided:

A) This sentence provides specific scientific detail about the conditions within blue holes and doesn't necessarily seem like a conclusion. B) This sentence pertains specifically to the current status of the Great Blue Hole as a tourist destination and seems more like a supporting detail than a concluding statement. C) This sentence explains the origins of the Great Blue Hole, which is an informative statement but may not serve as a conclusion unless the passage's focus was specifically the formation of the feature. D) This sentence places the Great Blue Hole in the context of other natural wonders around the world, suggesting a broader perspective that could be part of a summarizing statement in a concluding sentence.

Without context, it is challenging to provide a definitive answer, but if the passage was discussing the significance and the global context of the Great Blue Hole, Option D would likely serve as the best concluding sentence. It encapsulates the global significance of the feature by comparing it to other well-known natural wonders.