which type of IS-IS router can an IS-IS Level 2-only router form an adjacency?

With which type of IS-IS router can an IS-IS Level 2-only router form an adjacency?

A.
only other IS-IS Level 2 routers of the same area

B.
any IS-IS router

C.
any other IS-IS Level 2 router

D.
IS-IS Level 1 routers of the same area