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Medical AI Inquiry: You were designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.
user
In a study in the UK, an association was found between the sale of antiarrhythmic drug and an increase in deaths due to asthma. This is an example of
assistant
The correct answer is  Ans. is 'a' i.e. Ecological study Repeat May 08 www. ucel ac. uk. rlos/specs/rlo_observational_study. doc; http.//cancersupportivecare. com/epidemiology.html] For explanation see May 08