That sounds like a university to avoid.
But for an entrance exam, it's slightly hardcore :)
Unless you know the actual parsing rules, there's no way to know if a real parser would be greedy or not (or perhaps it might try to be clever?). This is nothing more than a trivia question, which does not test aptitude or intelligence.
I expect they asked some other questions too.
I had no idea how the C parsing algorithm worked for +++ et al, and I'm an expert C programmer. Then again, I'd also never use such ridiculous constructs in production code.
Even if you don't know that much about the subject, you can still have an interesting reasoning about it. Seeing that it is ambiguous is already a good observation. You then can propose way to resolve the ambiguity and touch (willingly or not) upon the topics of operator precedence, associativity, greedy matching.
Those topics are not only relevant in parsing either, for instance associativity is an important concept for list operations such as folding (a right fold is different from a left fold).