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

SLE (Single Loss Expectancy) is the estimated dollar value lost from a single occurrence of a threat, calculated as Asset Value x Exposure Factor, making it a monetary figure rather than a frequency measure.

Exposure Factor is a percentage representing the proportion of an asset's value destroyed in a single threat event, not a measure of how often the threat occurs.

ARO represents the estimated frequency - expressed as occurrences per year - at which a specific threat is expected to occur. It is a core variable in the ALE formula (ALE = SLE x ARO), where a value of 1.0 means once per year and 0.5 means once every two years. This makes it the metric that directly answers 'how often' a threat happens.

A safeguard is a security control or countermeasure implemented to reduce risk exposure, not a metric used to quantify or estimate threat frequency.