How do routers in an IS-IS Level-1 domain exit to reach other Level-1 (L1) domains ?(Select 2)

A.
Level-1(L1) routers use default routes announced by Level-2(L2) routers in Level-1(L1) domain

B.
Level-1 routers use default routes installed based on ATT bit (Attach Bit) in announcements from Level-1-2(L1/L2) router

C.
Level-1 routers use specific routes, for other Level-1 domain, announced by Level-1-2(L1/L2) by route-leaking feature of Cisco IOS

D.
Level-1 routers use specific routes, for other Level-1 domain, announced by Level-2(L2) by route-leaking feature of Cisco IOS