A．Those are cheap． 
B．Those are ethical． 
C．Those are unique． 
D．Those are comfortable． 

A．Zoos are not worth the public support． 
B．Zoos fail in their attempt to save animals． 
C．Zoos should treat animals as human beings． 
D．Zoos use animals as a means of entertainment．

A．He points out the faults in what Zoos do． 
B．He uses evidence he has collected at zoos． 
C．He questions the way animals are protected． 
D．He discusses the advantages of natural habitats．