"What you might have not expected is that BOTH the narrow metric and the wide metric are set to 63." "Because of the same reasoning behind advertising both metrics, the value of the wide metrics is limited by the limitations of the narrow metrics. Yes, that essentially defeats the purpose of using wide metrics." "Then, how do we fix it? Easy! Get rid of the narrow metrics! All your routers can do wide metrics these days (hopefully) thus, you don’t need to keep the narrow metrics. Just be aware that there are some side effects of changing from dual metrics to wide metrics only." https://momcanfixanything.com/isis-narrow-and-wide-metrics/

Bit tricky, but considering that the sole fact of having the wide metric enabled is not enough to take an advantage of the higher value because both the wide and narrow (the default) are enabled, then it is likely that answer B is correct. RFC reference: https://datatracker.ietf.org/doc/html/rfc3787#section-5 If not all devices in the IS-IS domain support wide metrics, narrow metrics MUST continue to be used. Once all devices in the network are able to support the new TLVs containing wide metrics, the network can be migrated to the new metric style, though care must be taken to avoid routing loops. In a nutshell we should configure wide metric only, in that way the narrow metrics will be disabled

It's b the answer

B is the correct answer