D

In an edge-to-edge (protrusive) position the contact occurs between the cutting edges of the mandibular incisors and the lingual (fossa) surfaces of the maxillary incisors. To relieve a premature contact you adjust whichever surface is responsible—either shorten the mandibular incisal edge or shallow the maxillary lingual fossa; both give the needed clearance, but it is rarely necessary to grind both simultaneously [Donegan & Knap, 1995, PMID 8601179].