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
[{'content': 'During normal vaginal delivery, deep transverse arrest occurs. Ventous was employed for the safe delivery. This mother may have the following type of pelvis: \nSelect and explain. \nA. Flat sacrum and convergent side walls, B. Gynaecoid, C. Platypelloid, D. Anthropoid', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Criteria for the deep transverse arrest: The head is deep into the cavity. The sagittal suture is placed in the transverse bispinous diameter and, There is no progress in descent of the head even after 1/2 -1 hour following full dilatation of the cervix. Causes of deep transverse arrest: Faulty pelvic architecture such as prominent ischial spines, flat sacrum, and convergent side walls Deflexion of the head Weak uterine contraction Laxity of the pelvic floor muscles Ref: Textbook of Obstetrics by DC Dutta, 6th edition, Page 372.', 'role': 'assistant'}]