Answer:
b.security event.
Step-by-step explanation:
A security event is an deviation or change in the daily operations of information technology service that gives a warning that security policies have been violated or a safeguard has failed.
Significance of a security event is measured by effect on hardware, software, data, or security of systems.
For example if a user contracts a computer virus it is a security event, because this means a security breach occured. Antivirus products are security software that reduces occurrence of security event.