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: Gynaecology & Obstetrics
Least failure in sterilization occurs with: 
Select and explain. 
A. Falope ring, B. Bipolar cautery, C. Unipolar cauterisation, D. Hulka clip
C: Unipolar cauterisation
Answer: C: Unipolar cauterisation 
Explanation: Female tubal sterilization methods-10 year cumulative failure rates:
Unipolar cauterisation – 0.75%
Postpartum tubal excision – 0.75%
Silastic ring/fallope ring – 1.77
Interval tubal exclusion – 2.01
Bipolar coagulation – 2.48
Hulka - clemens clips – 3.65
Note: Although unipolar cauterization has least failure rates, but is not preferred method for female steriliization as it leads to serious gastrointestinal burns.