ResultSet is an interface. It doesn't extend Serializable, so one cannot guarantee that all ResultSets will be Serializable. In theory, some implementations of ResultSet might be Serializable, although probably not, as it doesn't sound like a good idea to me.
Betty Rubble? Well, I would go with Betty... but I'd be thinking of Wilma.
I'm surprised no one has replied with my first answer to the question:
That's a bad idea, what are you really trying to do?
In 99% of the cases, you want to see either the whole result set, or some aggregated function (ave(cost)) over the rows. So send either the array or the answer, don't make the calling code handle all the cruft of a ResultSet.