I would have picked ‘C’.
As observed by LeadSled earlier in the thread, the 10 minute margin has been in AIP forever. I suspect that deep in the bowels of the transitional provisions from the ANRs/ANOs to CARs/CAOs there will be some savings provision for a piece of parchment, issued by the Secretary under the ANRs or ANOs while the Harbour Bridge was being built, determining the 10 minute margin requirement.