A.
At that age, my daughter loved the lemurs / other small monkeys and the camels. She also liked the giraffes. She was also a huge fan of the farm animals. We have been regular zoo visitors (Lincoln Park) since she was 10 months old. She's now 26 months, and she begs for the zoo. She talks about the animals and the zoo all day long. Her daycare teachers honestly thought we stopped there daily on our way home! We go at least 2x a month.
(FYI - even though Lincoln Park zoo is free, if you plan to go and park more than 7 times in one year, a Zoologist level membership pays for itself. You get free parking year round. We've gotten our money's worth and then some...)