What can we learn from the above information?

The customer’s six switches SWA, SWB, SWC, SWD, SWE, and SWF are connected together through a LAN to form an RRPP ring. The RRPP status is checked on SWB as follows:

<SWB>dis rrpp verbose domain 1 Domain ID: 1

Ring ID: 1 Ring Level: 0

Node Mode: Transit Ring state: –

Enable Status: YesActive Status: Yes

Primary port: GigabitEthernet2/0/1 Port status: UP Secondary port: GigabitEthernet2/0/2 Port status: UP Ring ID :2

Ring Level: 1 Node Mode: Edge Ring state: –

Enable Status: YesActive Status: Yes

Common port: GigabitEthernet2/0/1 Port status: UP GigabitEthernet2/0/2 Port status: UP

Edge port: GigabitEthernet2/0/3 Port status: UP Ring ID: 3

Ring Level: 1

Node Mode: Edge Ring state: –

Enable Status: YesActive Status: Yes

Common port: GigabitEthernet2/0/1 Port status: UP GigabitEthernet2/0/2 Port status: UP

Edge port: GigabitEthernet2/0/4 Port status: UP

What can we learn from the above information?
A . SWB is the transit node of RRPP sub-ring 2
B . SWB is connected to 3 sub-rings
C . GigabitEthernet2/0/1 is the edge port of RRPP sub-ring 2
D . GigabitEthernet2/0/4 is the edge port of RRPP sub-ring 3