Which of the following could be found on either public or private land?

The answer is C. mines

The option that could be found on either public or private land is C. mine. A state park can only be found on public land, because parks are owned by states, not regular people. A single-family residence is only found on private land, because that is a house that a family owns. A factory is on private land only, because it belongs to a person or another company. Which leaves us with mines, that can be found both on private and public lands.