As shown in the figure, enterprise A and enterprise B need to communicate securely, and an IPSec tunnel is established between firewall A and firewall B. Which of the following security protocols and encapsulation modes can meet the needs of this scenario?

As shown in the figure, enterprise A and enterprise B need to communicate securely, and an IPSec tunnel is established between firewall A and firewall B. Which of the following security protocols and encapsulation modes can meet the needs of this scenario?
A . AH, tunnel mode
B . ESP, tunnel mode
C . ESP, transmission mode
D . AH+ESP, transmission mode

Answer: B