Which of the following terms related to risk management represents the estimated frequency at which a threat is expected to occur?

Single Loss Expectancy (SLE) represents the estimated monetary loss resulting from a single occurrence of a threat event, not the frequency of occurrence.

ARO is defined in quantitative risk analysis as the estimated number of times a given threat event is expected to occur per year. It is a key input in calculating Annualized Loss Expectancy (ALE = SLE x ARO), making it the direct measure of threat frequency. For example, an ARO of 0.5 means the threat is expected once every two years.

A safeguard (also called a countermeasure or control) is a protective measure implemented to reduce risk - it is an action or mechanism, not a frequency metric.

Exposure Factor (EF) is the percentage of an asset's value that would be lost in a single threat occurrence, representing impact magnitude rather than occurrence frequency.