I think human communication and therefore speech is seldom governed by strict logic and (luckily) more often driven by our personality, experience, context, and eventually roles and authority of the persons interacting. If you are answering to a QUIZ on TV, of course you should only say one subject, but if someone makes you that question in an job interview, or in a friendly environment, then you are the only good judge for deciding over a minimal or extended answer, and I think this fact to be independent from the language. Please excuse me for all these words, I am not able to make it shorter! I realize now that Chris told you quite the same!