What bit should be set in the link state PDUs in an IS-IS level-1-2 router to indicate that they are a potential exit point out of the area?

What bit should be set in the link state PDUs in an IS-IS level-1-2 router to indicate that they are a
potential exit point out of the area?

A.
ATT (Attached) bit

B.
ABR (Area Border Rorter) bit

C.
PN (Pseudonode) bit

D.
P (Partition) bit

E.
Down bit

F.
IS-Type bit