When capturing the data that Site2 visits the 192.168.1.0/24 of Site1 between P and PE1, what should be the outermost label?

As shown in the figure, Site1 and Site2 need to achieve mutual access through the operator’s BGP/MPLS IPVPN. It is known that the public network tunnel between PE1 and PE2 has been established (the label information is shown in the figure), and PF1 has advertised the 192.168.1.0/24 network segment route in Site1 to PE2 through the MP.JIBGP neighbor relationship, and the route learning is normal.

When capturing the data that Site2 visits the 192.168.1.0/24 of Site1 between P and PE1, what should be the outermost label?
A . 6661
B . 3
C . 6662
D . 8888

Answer: D