In the context of information security, risk is typically calculated as the product of likelihood and impact. This formula encapsulates the probability of a vulnerability being exploited (likelihood) and the potential damage or loss that could result from such an event (impact). The goal is to quantify the level of risk in order to prioritize mitigation efforts effectively. Options B, C, and D do not represent standard risk calculation formulas in information security management.

References: The BCS Foundation Certificate in Information Security Management Principles outlines the importance of understanding risk management within the domain of information security. It emphasizes the need for calculating risks to inform security controls and decision-making processes1. Additionally, ISO 27001, a leading international standard for information security management systems, also supports the formula of Risk = Likelihood * Impact as part of its risk assessment and treatment methodology2.