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
Duration of latent phase of labour is affected by :a) Early use of conduction anaesthesia and sedation b) Unripe cervixc) Hypertonic uterine contractiond) Pre-eclampsia 
Select and explain. 
A. ac, B. a, C. ad, D. ab
D: ab
Answer: D: ab 
Explanation: None