So here is another nice little puzzle based on set theory, with a perfectly plausable senario.
Ok so the puzzle goes like this, imagine you have an office where everybody drinks coffee,
they all drink coffee everyday, and they get their coffee in exactly one of two ways:
Option A) Either they go and make it themselves, or
Option B) The secretary makes it for them.
Another way to explain this is:
The secretary is only person in the office who makes coffee for those who don't make it
themselves.
The question is: Who makes coffee for the secretary and which option is this?