Which of the following is not a ‘Public Good’?

Which of the following is not a ‘Public Good’?

Electricity
National Defence
Light House
Public Parks
This question was previously asked in
UPSC CDS-1 – 2016
Electricity is not considered a ‘Public Good’ in the economic sense.
– A pure public good is characterized by two main properties: non-excludability (it is difficult or impossible to prevent people who have not paid for it from consuming it) and non-rivalry (consumption by one person does not reduce the amount available for others).
– National Defence is a classic example of a public good: defending the nation benefits everyone, and one person’s security does not diminish another’s (non-rivalrous); it is impossible to exclude any citizen from receiving this benefit (non-excludable).
– A Lighthouse is also often cited as a public good: ships can benefit from the light without paying (non-excludable), and one ship using the light doesn’t stop others from using it (non-rivalrous).
– Public Parks can be considered common resources or quasi-public goods. While often publicly provided, they can suffer from rivalry (overcrowding) and sometimes even excludability (fenced parks with entry fees or limited access).
– Electricity is a private good or, in some distribution scenarios, a club good. It is excludable (utility companies can cut off service to non-payers) and rivalrous (the amount of electricity consumed by one household reduces the amount available in the grid capacity).
Goods are classified into different types based on excludability and rivalry: Private Goods (Excludable, Rivalrous), Public Goods (Non-excludable, Non-rivalrous), Common Resources (Non-excludable, Rivalrous), and Club Goods (Excludable, Non-rivalrous, at least up to capacity).