What is called the standard format that was established to set up and manage Security Associations (SA) on the Internet in IPSec?

What is called the standard format that was established to set up and manage Security
Associations (SA) on the Internet in IPSec?

A.
Internet Key Exchange

B.
Secure Key Exchange Mechanism

C.
Oakley

D.
Internet Security Association and Key Management Protocol

Explanation:
Reference: pg 221 Krutz