The most difficult question concerned giving a response in a context that I was not familiar with. I was given a question in my area of domain and asked to apply it on Bangladesh, a country I knew nothing about. The purpose of such questions is to see whether the candidate is able to use their knowledge in different contexts and to modify the approach and thinking based on the country specific context. Such questions almost always come up at interviews and the best answer is to make some assumptions about the context in case you are not familiar with it.