The best example of a public good among the options provided is Yellowstone National Park.
Public goods are typically defined by two main characteristics: they are non-excludable (once they are provided, it is difficult to prevent anyone from accessing them) and non-rivalrous (one person's use of the good does not diminish its availability to others). Yellowstone National Park fits these criteria, as it is open to the public, and while there are limits to the number of visitors for environmental reasons, one person's visit does not prevent others from enjoying the park as well.
In contrast, the other options (a cartoon-themed amusement park, a membership-only country club, and a shopping mall) are all excludable and may be rivalrous, thus categorizing them as private goods rather than public goods.