You want to use IS-IS on a GRE interface where the underlying Layer 3 MTU is 1500.

Which statement is correct in this scenario?

A. IS-IS can be used because every IS-IS interface must be capable of transmitting packets at least as large as 1476 bytes, and the GRE header is 24 bytes.

B. IS IS can be used, but the networking device directly attached to the circuit must be capable of fragmentation.

C. IS-IS cannot be used, but the router can enable a GRE key that serves the same function as IS-IS.
D. IS-IS cannot be used because the IS-IS hello is not allowed to be fragmented and has the DF bit set.

Reference: https://kb.juniper.net/InfoCenter/index?page=content&id=KB7848