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
After mixed dentition stage, the arch length from first molar to first molar usually: 
Select and explain. 
A. Remains same, B. Increases, C. Decreases, D. Double
C: Decreases
Answer: C: Decreases 
Explanation: Decrease in arch length : The arch decreases in the mixed and permanent dentition stages as a result of the uprighting of the incisors and the loss of the leeway space by the mesial movement of the first permanent molars.
Text book of orthodontics Gowrishankar 1st Ed P:92