The best criterion for prioritizing risks in the context of probability assessment is to evaluate how often a given security incident could occur within a specified time period, such as a year. This evaluation is fundamental to understanding the annualized rate of occurrence, which helps determine how resources should be allocated for mitigation strategies. A higher frequency indicates a higher probability of occurrence, which usually results in a higher priority for control implementation. While other options like the features of latest security technologies implemented, the number of software updates per week, and the historical time between successful incidents could inform various aspects of the security posture, they do not directly assess probability for prioritization of risks.