Give examples of situations that reveal altruism and egoism. Do you believe that the basis of morality is altruism or egoism?

Give examples of situations that reveal altruism and egoism. Do you believe that the basis of morality is altruism or egoism? Or is it perhaps an absolute moral code either handed down to us by previous generations from an original revelation by God? Or is it based upon self-evident moral principles which one should follow whether or not it furthers either our own interests or the interests of others? Should we do right simply because it is prima facile right? Give reasons for holding your view.