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': 'True about lecithin - sphingomyelin ratio is \nSelect and explain. \nA. Concentration of Lecithin and sphingomyelin before 34 weeks in amniotic fluid is equal, B. Concentration of Lecithin is more than sphingomyelin in amniotic fluid before 34 weeks., C. After 32 to 34 weeks, concentration of sphingomyelin relative to Lecithin begins to rise, D. There is increased risk of Respiratory distress syndrome if L/S ratio is > 2', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Concentration of lecithin relative to sphingomyelin begins to rise at 32 - 34 weeks. L / S ratio < 2 suggests high risk of RDS.', 'role': 'assistant'}]