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
Risk factor for preeclampsia:a) Chronic hypertensionb) Smokingc) Obesityd) Multiparitye) Placenta previa 
Select and explain. 
A. a, B. bc, C. ac, D. b
C: ac
Answer: C: ac 
Explanation: None