The answer is B) Oracle of Delphi. The other items are tied to other elements. For example, A) the riddle does not apply to Delphi, but rather represents the Sphinx. Oedipus does not consult a mountain at Delphi, as he is searching for answers, the Corinthian messenger brings news, and does not possess answers in his own right. Oedipus' consultation of the Oracle at Delphi is the best answer present. The Oracle at Delphi is where guidance is given and where clarity is sought. It is als the vessel of the God Apollo, heightening its significance to Sophocles' drama. In Act III, we see Jocasta pray to the God Apollo to restore sanity back to her husband and in the Prologue, Oedipus, seeking answers as king, sends Creon to the Oracle of Delphi to determine why the citizens of Thebes are being subjected to troubles that have overcome them. In the end, the answer would have to be B) Oracle of Delphi.