This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
8 year-old child had fractured his maxillary central incisor
10-months ago. The pulp shows no response. There is no periapical lesion in the radiograph. The treatment of choice is: 
Select and explain. 
A. Ca(OH)2 pulp capping, B. Formocresol pulpotomy, C. Conventional root canal treatment, D. Complete debridement and apexification
D: Complete debridement and apexification
Answer: D: Complete debridement and apexification 
Explanation: Apexification 
Definition
“Apexification is defined as chemically induced root formation by calcium hydroxide or CMCP in nonvital immature, blunderbuss canals of young permanent teeth.”
APEXIFICATION 
It is a method of inducing apical closure by formation of mineralized tissue in the apical region of a nonvital permanent tooth with an incompletely formed root apex. 
It is defined as a method to induce development of the root apex of an immature pulpless tooth by formation of osteocementum/bone-like tissue (Cohen). 
Apexification is a method of inducing apical closure through the formation of mineralized tissue in the apical pulp region of a nonvital tooth with an incompletely formed root and an open apex (Morse et al. 1990).