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
Which of the following is not an indication for a class II
activator: 
Select and explain. 
A. Mandibular retrusion, B. Horizontal/anterior type of mandibular growth, C. Crowding lower anteriors, D. Upright lower anteriors
C: Crowding lower anteriors
Answer: C: Crowding lower anteriors 
Explanation: Class-II and III malocclusions, class-I open bite and deep bite malocclusions, children with lack of vertical development in lower facial height, and upright mandibular incisors are indications of activators.
Activators may produce moderate mandibular rotation (anteriorly down words), so they are contraindicated in vertical growers.