A 'One-Time' risk assessment is a standalone evaluation conducted to assess the risks associated with a specific event or change, such as the introduction of a new business initiative. It helps in identifying potential risks before proceeding with the project and is not part of the regular, scheduled assessments. This type of assessment is critical for making informed decisions about one-off projects or changes that are not part of the routine operational activities. 'Ad Hoc', 'Recurring', and 'Continuous' assessments are incorrect because they respectively describe assessments that are unscheduled and irregular, regularly scheduled, and ongoing monitoring.