(Topic 1) If two routers running IS-IS protocols are exchanging Hello packets with different authentication types, which of the following statements regarding the adjacency state established between them is true?

(Topic 1) If two routers running IS-IS protocols are exchanging Hello packets with different authentication types, which of the following statements regarding the adjacency state established between them is true?
A . Different authentication types are not possible because IS-IS only supports password authentication.
B . An adjacency will not be formed
C . The two routers negotiate the authentication type and then reach the up state.
D . Only an L2 adjacency will form, as long as both routers are L2 capable.

Answer: B