Which statement is true about IS-IS?

Which statement is true about IS-IS?

A.
IS-IS level 1 internal routes are announced to level 2 by default.

B.
All IS-IS level 1 routes are announced to level 2 by default.

C.
IS-IS level 2 internal routes are announced to level 1 by default.

D.
IS-IS does not share routes between level 1 and level 2 by default.