Q:"''Nous sommes professeurs.'' Who can be speaking?" A: "Georges" - Why?

Question

I understand about mixed gender and singular/plurals, but this strikes me as a misleading question - the other options were the standard mix of genders, but I would assume if only person was speaking (Georges), then the question means who is this referring to, not speaking, and so this would not be a correct answer.
I don't think this is a case of misunderstood grammar, just a poorly phrased question. What I think the writer had in mind was that just George was speaking, and was referring to himself and someone else, but the other answers all imply one person speaking, unless two people were speaking at exactly the same time (unlikely!), e.g. "Georges and Fiona".

Anyone care to shed light on the matter before I report?

Answer

I agree, James, the question is poorly phrased. It can be interpreted in a way that all choices are correct, i.e., Georges is speaking and referring to an (unmentioned) group of people.
But even without this, the question doesn't really test whether you can distinguish the male or female version of professeur. It just tests whether you know that sommes refers to more than one person.