Interview Question for Business Analyst at Deloitte:

Another potential answer is citing the fact that you have reach back into a very large pool of specialized resources with years of experience. In this case you would ask a lot of questions and take the information back to some SMEs in the firm. They will help you come up with recommendations. This situation is rare but not impossible. I've been in a similar one before. Just be honest and tell the client that you can provide better advice if you gather some information and take it back to a few colleagues.