The correct answer is C.
A public good is one that whose ownership is shared collectively by a group of individuals.
These type of goods are non-rival in the sense that if one person is consuming it, that does not prevent simultaneous consumption by a different person. Also, it implies that if one individual consumes the good, this does not reduce its availability for a subsequent consumer. For example, imagine a public park.
Morover, they are nonexcludable as it is not possible to exclude does who have not paid for the good from its consumption. For example, public parks are financed with tax income but access to them is not banned to those who have not met their tax payment obligations .