Which two factors are crucial in calculating the likelihood of an event?

The correct choice emphasizes the relationship between threat and vulnerability, which is fundamental in assessing the likelihood of an event occurring in the context of cybersecurity. A threat represents a potential danger that could exploit a vulnerability, leading to an event that can compromise the security of an asset.

Understanding the interaction between these two factors is essential; if there is a significant threat and a corresponding vulnerability that has not been mitigated, the likelihood of a negative event occurring increases. By evaluating how these elements work together, organizations can better anticipate potential risks and prioritize their cybersecurity measures.

In contrast, the other options include factors that, while related to security and risk management, do not directly calculate the likelihood of an event in the same manner. For instance, impact and consequence are more about assessing what happens if an event occurs rather than focusing on the chances of it occurring, while risk itself is a broader term that encompasses various factors, including but not limited to threat and vulnerability. Exposure and mitigation deal with how vulnerable assets are affected and the strategies in place to lessen risks, but they don't directly address the fundamental probabilities involved in an incident.