Opportunities, according to ISO standards such as ISO 31000, are situations or conditions that have the potential to provide a favorable impact on achieving objectives. They represent circumstances that, when leveraged, can lead to beneficial outcomes for the organization, such as competitive advantage, growth, or improved performance. Option B is correct as it accurately describes opportunities as circumstances expected to be favorable to achieving objectives. Option A (Occurrence or change of a particular set of circumstances) is a more general definition that could apply to both risks and opportunities, while Option C (Outcome of an event affecting objectives) is more aligned with the concept of risk.