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 protapers have almost similar size of the tip? 
Select and explain. 
A. S1 & Sx, B. S1 & S2, C. S2 & F1, D. S2 & L1
C: S2 & F1
Answer: C: S2 & F1 
Explanation: None