Answer: C
M26.03 is the correct code for this patient because it codes for mandibular hyperplasia which is the diagnosis here. Due to jaw enlargement of the lower arch, the condition is mentioned as mandibular hyperplasia.
Option A is not correct because M26.01 is used to code for maxillary hyperplasia. Here, hyperplasia is in the mandible.
Option B is not correct because M26.02 is used to code for maxillary hypoplasia. Here, maxillary hypoplasia is not the diagnosis.
Option D is not correct because M26.04 is used to code for mandibular hypoplasia. Here, hyperplasia is the diagnosis instead of hypoplasia.