Which option is a defining feature of pay-per-view television as a good?

Pay-per-view television is characterized by low rivalry and high excludability, which is why this option is the defining feature of the good.

In terms of rivalry, pay-per-view programming allows multiple viewers to access the same content simultaneously. One person purchasing a pay-per-view event does not prevent others from watching it at the same time—this exemplifies low rivalry. Thus, the nature of this service allows many individuals to enjoy the programming without one person's enjoyment diminishing another's.

On the other hand, high excludability refers to the ability of the provider to restrict access to the service. In the case of pay-per-view television, access is limited to those who have made a payment to view the content. Service providers can effectively control who watches by requiring payment, thereby excluding non-paying individuals from accessing the program.

This combination of low rivalry and high excludability is a hallmark of how pay-per-view services operate in the market.