Refer to the exhibit. An engineer configures EIGRP but the routers fail to form a neighborship. What is the reason for the failure?

Invalid K-values would prevent neighborship but are not the primary cause when authentication is misconfigured, as implied by the choices.

While MD5 digests not matching causes failure, the key ID mismatch is a more specific and fundamental authentication configuration error that would lead to a digest mismatch.

For EIGRP authentication to succeed, both the key ID and the key string (MD5 digest) must match between neighboring routers. If the key IDs do not match, the authentication process fails, and the EIGRP neighborship will not form.

EIGRP can form a neighborship even if hold timers do not match; the router with the shorter hold timer will simply declare the neighbor down sooner.