Information security risk, as defined by ISO/IEC 27005, is "the potential that a threat will exploit a vulnerability of an asset or group of assets and thereby cause harm to the organization." This definition emphasizes the interplay between threats (e.g., cyber attackers, natural disasters), vulnerabilities (e.g., weaknesses in software, inadequate security controls), and the potential impact or harm that could result from this exploitation. Therefore, option A is the most comprehensive and accurate description of information security risk. In contrast, option B describes a vulnerability, and option C focuses on the cause of an incident rather than defining risk itself. Option A aligns directly with the risk definition in ISO/IEC 27005.