What Event(s)led Common People to Question Whether Humans Were Really

What event(s) led common people to question whether humans were really unique creatures,totally unlike other species?​

A) ​Many took cruises to South America and other places where they were exposed to species of apes very similar to human beings.
B) The tenet of natural selection became widely known and popular.
C) ​Displays of orangutans and chimpanzees became common in zoos,as well as fossil comparisons of gorilla and human skeletons.
D) Helmholtz's and Fechner's research findings made such questioning inevitable.
E) None of the choices are correct.