Which of the following security association techniques uses multiple layers of protocols through IP tunneling?

Which of the following security association techniques uses multiple layers of protocols through IP tunneling?

A.
Iterated

B.
Transport adjacency

C.
Encapsulation

D.
Replay

Explanation:
In an iterated association each tunnel can originate or terminate at a
different IPSec site along the way. This method supports multiple layers of nesting.