Which of the following is a consequence of non rivalry in public goods?

Non-rivalry is a fundamental characteristic of public goods, meaning that one person's consumption of the good does not diminish the availability of that good for others. This quality leads to the realization that the marginal cost of allowing an additional individual to consume the good is effectively zero.

For example, once a public good, like a national defense system or a streetlight, is provided, one more person benefiting from it does not reduce the benefit experienced by others. No additional resources are needed to provide this extra benefit, as the good remains available for everyone without any extra cost involved.

The other options, while related to the context of public goods, do not correctly illustrate the implications of non-rivalry. Increased consumption does not lead to decreased availability, as public goods are available for all. Paying customers do not receive a better quality of public goods because these goods are meant to serve everyone equally, and consumption is not restricted to those who pay, contrasting with private goods where payment often entitles better quality or exclusivity. Thus, the characteristic of non-rivalry leads directly to the conclusion that the marginal cost for additional consumption is zero, making the correct choice clear.