What characteristic defines a good that is excludable?

A good is defined as excludable when individuals can be prevented from using it if they do not pay for it. This characteristic allows producers to charge consumers for the good, as they can limit access to only those who have made a purchase. In essence, excludable goods can generate revenue because non-payers can be effectively excluded from their consumption.

Other characteristics mentioned in the answer choices highlight different aspects of goods. For instance, a good that is available for use by anyone without restriction would be classified as non-excludable. Likewise, a good that is available to all regardless of payment emphasizes the idea of non-excludability. Lastly, the concept of being rival in consumption relates to whether one person's consumption of the good diminishes the ability of others to consume it, which is a different attribute than excludability. Thus, the definition provided in the chosen answer distinctly captures what it means for a good to be excludable in economic terms.