This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Which of the following is not a feature of a cross sectional study - 
Select and explain. 
A. Not expensive, B. Observational study, C. Used for chronic diseases, D. Well suited for establishing interrelationships of diseases
D: Well suited for establishing interrelationships of diseases
Answer: D: Well suited for establishing interrelationships of diseases 
Explanation: The time sequence which is essential to the concept of causativity can't be deduced from cross-sectional data. (refer pg no:69 park 23rd edition)