If aggressive mode is not selected for your IPSec tunnel, the gateway defaults to main mode, performing the IKE negotiation using how many packets during phase 1 exchange?

If aggressive mode is not selected for your IPSec tunnel, the gateway defaults to main mode, performing the IKE negotiation using how many packets during phase 1 exchange?

A.
2

B.
3

C.
9

D.
12

E.
6