I completely agree with authorities that this is a proper question to ask. I am curious about the answer. Most Chinese people tend to say 'cheers' which is wrong. Cheers means take a drink. The true meaning of 'ganbei' is "bottoms up". Bottoms up means the bottom of your glass should be above your mouth while you empty your glass. In my years of teaching in China, I have never met a student who knew the correct answer. I think this was an excellent question in the exam as it is truly very important to create a good first impression with foreigners.