In instrumental vaginal delivery:: (A) Full cervical dilatation is the only pre-requisite, (B) Forceps are used in all cases of breech delivery, (C) Forceps may be used if ventouse fails, (D) Ventouse can not be used in rotational occipito-transverse/posterior delivery
Answer is C. In case of failed ventouse, forceps may be used. Ref: Textbook of Obstetrics By Dutta, 4th Edition, Pages 397, 398, 613-614