Private property rights 0 are rights to ownership but are not vital for well-functioning markets. 0 are rights to ownership and are vital for well-functioning markets. 0 make voluntary trade impossible. 0 require all citizens to own property. A positive externality occurs when O all the benefits to society are not captured in the private demand curve. O all the costs to society are not captured in the private demand curve. O all the benefits to society are not captured in the private supply curve. O all the costs to society are not captured in the private supply curve.One reason it can be difcult to fund a public project such as a park with no entrance fee is 0 there will be so much competition from private companies who want to own the park. 0 the free rider problem. 0 only those who really value the park will pay for it. 0 no one will pay for the park