Which of the following BEST demonstrates that an anti-phishing campaign is effective?

The ultimate goal of an anti-phishing campaign is to reduce the risk and impact of phishing attacks on the organization. Therefore, the most relevant and reliable indicator of the effectiveness of an anti-phishing campaign is the decreased number of incidents that have occurred as a result of phishing. This metric shows how well the employees have learned to recognize and report phishing emails, and how well the security controls have prevented or mitigated the damage caused by phishing.

References = Five Ways to Achieve a Successful Anti-Phishing Campaign; Don’t click: towards an effective anti-phishing training. A comparative literature review; CISA, NSA, FBI, MS-ISAC Publish Guide on Preventing Phishing Intrusions