Final answer:
A park would be considered a public good when visitors can enter the park free of charge and there are always plenty of empty picnic tables available option C is correct.
Step-by-step explanation:
The correct scenario out of the given options in which a park would be considered a public good is option c. Visitors can enter the park free of charge and there are always plenty of empty picnic tables.
A public good is defined as a good or service that is non-excludable and non-rivalrous. Non-excludable means that it is impossible or very costly to exclude someone from using the good, and non-rivalrous means that one person's use of the good does not diminish its availability to others.
In option c, the park is freely accessible to all visitors without any admission fee, which meets the non-excludable criterion. Additionally, since there are always plenty of empty picnic tables available, one person's use of a table does not diminish its availability for others, fulfilling the non-rivalrous criterion.