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 10 years old boy comes to the clinic presenting with a distal step molar relation in the mixed dentitional stage. He would most probably need which of the following appliances? 
Select and explain. 
A. Nance holding arch, B. Oral screen, C. Functional regulator, D. Space maintainers
C: Functional regulator
Answer: C: Functional regulator 
Explanation: Nance holding arch is a space maintainer. The boy in this case is having class III tendency. So a myofunctional appliance is required to correct this. Oral screen is used to intercept habits, to perform muscles exercises and to correct mild anterior proclination.