What is not a specific type of attack, but refers to most attacks that occur today?

A.
DoS

B.
Brute force password

C.
IP spoofing

D.
Unauthorized access

Explanation:
Although unauthorized-access attacks are not a specific type of attack, they refer to most attacks executed in networks today.
REF;Safe white papers;page 70
SAFE: Extending the Security Blueprint to Small, Midsize, and Remote-User Networks