This is a loaded political question. But I think the question is trying to get you to think about who is doing the best for society as a whole and who is thinking about doing what's best for them.
However, some would argue that doing what's best for yourself will also lead to the greater good of society, but I think this question (as unfair as it may be), is leading you to say that democrats are more concerned with achieving broad happiness and republicans are concerned with fulfilling selfishness.