This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General obstetrics, Subject name: Gynaecology & Obstetrics
What is the risk of downs syndrome in a 35-year-old pregnant woman? 
Select and explain. 
A. 1 in 75, B. 1 in 100, C. 1 in 250, D. 1 in 1000
C: 1 in 250
Answer: C: 1 in 250 
Explanation: Age of the motherRisk of Down&;s syndrome351 in 250361 in 192371 in 149381 in 115391 in 89401 in 69Reference: William's obstetrics; 25th edition; Chapter 14; Prenatal Diagnosis