Which of these animals is one of the tiger's most common prey?

Tigers primarily hunt deer, but as opportunistic predators, they can also eat wild boars, birds, fish, rodents, amphibians, reptiles, and even insects. A large deer can provide a tiger with one week's food, but only one out of every ten hunts is successful. Tigers don't usually eat their prey at the kill site - but instead drag their prey into cover to feed. If a tiger leaves - say to get a drink - it will cover its kill by raking leaves, dirt, grass and even rocks over the carcass.

Source: WWF