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: Surgery
Primary rotation force is applied for the extraction of: 
Select and explain. 
A. Max. central incisor + Mandibular 2nd premolar., B. Max. central incisor + Mandibular central incisor., C. Max. premolars., D. All of the above.
A: Max. central incisor + Mandibular 2nd premolar.
Answer: A: Max. central incisor + Mandibular 2nd premolar. 
Explanation: None