A zero-day (or zero-hour) attack or threat is a computer threat that tries to exploit computer applicationvulnerabilities which are unknown to others, undisclosed to the software vendor, or for which no security fix is available. In order to prevent this attack occurring, which security mitigationtechnique can be used?

A.
Effective security policies

B.
Update antivirus definitions

C.
MAC filtering

D.
User awareness training