This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abnormal labor, Subject name: Gynaecology & Obstetrics
True about vacuum extraction of fetus: 
Select and explain. 
A. Can be used in nondilated cervix, B. Can be used in incompletely dilated cervix, C. Used in face presentation, D. Applied 3 cm posterior to anterior fontanel
B: Can be used in incompletely dilated cervix
Answer: B: Can be used in incompletely dilated cervix 
Explanation: indications fetal distress in second stage Maternal distress in second stage Prolonged second stage Deep transverse arrest and persistent occipito-posterior High vacuum for second twin (refer pgno: 447 textbook of obstetrics sheila 2 nd edition)