1 Traditional, barred cages are almost absent from modern zoos. 2 Instead, animals in modern zoos live in surroundings similar to their natural environment in the wild. 3 Artificial storms are designed, and deserts are constructed, to meet the needs of a wide variety of beasts, fish, and fowl. 4 Fish exhibits are particularly popular at zoos. 5 Tape recordings of familiar noises are used to soothe animals and help them adjust to new homes. 6 Gorillas, for example, often become sluggish in captivity. 7 They become more active when exposed to recordings of sounds that they would encounter in African mountain forests. Which sentence could you remove from the paragraph to improve its unity?