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
A 7-years girl with single tooth crossbite came to clinic what should be treatment plan: 
Select and explain. 
A. Wait till all permanent teeth erupt, B. Removable appliance therapy, C. Immediate intervention therapy, D. Extraction of tooth
C: Immediate intervention therapy
Answer: C: Immediate intervention therapy 
Explanation: None