Hmm... Not math, but interesting!
I'm not so good at these types of problems, please forgive me if this isn't the answer that you wanted (I messed up super bad on another problem!)
Here we go:
I believe that the sample is biased because it does not represent the population - The City did not get random coaches, so it isn't random.
I also believe that the question is not biased - because both water and the sports drink are given equal opportunity. UNLESS you count in the order, where drinking water is presented first as an option, and therefore has a slight psychological effect upon the participant's mind. :)
My own thoughts -- probabaly not professional. :)