Me with this question you xoxo excerpt from the great blue hole rebecca sparling 4the poor water circulation inside most blue holes makes them anoxic. this means that oxygen levels are extremely low at certain depths. the unfavorable environment makes it difficult for marine plants and animals to survive, but large numbers of bacteria seem to flourish in these holes. some divers claim to spot the occasional shark in the deeper parts of the hole where the water is much clearer. explorers and scientists believe that a series of underwater tunnels might connect the hole to the mainland. the hazards of exploring such a network make this theory difficult to verify. according to section four of this passage, bacteria flourish inside the great blue hole. from this information you can tell that a) the great blue hole is polluted. eliminate b) bacteria thrive in deeper waters. c) bacteria are not well understood. d) bacteria need little oxygen to survive.