Read the passage and complete the sentence.
US zoologists completed a list of living beings according to their ability to cross the street safely. They claim that the goose is the first on this safety list. It is very seldom that he gets run over. The pig and the cat placed the second and third respectively, then follow the hen and dog. Believe it or not, man is the last on this curious list. ... were the first to observe living beings cross the street safely.