The success rate of social engineering attacks directly measures the behavioral changes resulting from an information security awareness program. Employees who are aware and informed are better equipped to identify and thwart such attacks.

Reduction in Reported Incidents (Option A):This may indicate underreporting rather than program effectiveness.

Reduction in Cost of Maintaining the Program (Option C):This reflects cost efficiency, not program effectiveness.

Reduction in Number of Attacks (Option D):The number of attacks is beyond the control of awareness programs and does not reflect their impact.