if ya know za answer three60 then spillz,
i think i know the answer to the 2 extra credit questions but not za real one
edit:
That would be the riddle of the sphinx,
The sphinx in Greece asks that question.
the answer is 'Man' (A baby crawls on all fours, then a man walks up right, then an old man walks with a cane)
im not sure about the 3rd one but i think this is it
The sphinx in Greece guard the entrance to the city of Thebes
for an extra, extra, extra credit,
Oedipus is the person who has said to answer the question