According to the given paragraph, Zoos are important because they protect animals and help keep them from going extinct.
There is currently ongoing work by the Wildlife Conservation Society to re-release the animals into their habitat.
There are also other programs which are designed to educate the public about the importance of the zoo and also the animals in them.
Therefore, the sentence that is part of the evidence in this paragraph is Sentence 3, because it gave evidence that the National Zoo in Washington D. C. has bred Sumatran tigers, boosting a population that was once only seven hundred in the wild.
