After her husband was murdered at a crossroads, which queen's hand in marriage was promised to whoever solved the Sphinx's riddle?

The queen whose hand in marriage was promised to whoever solved the Sphinx's riddle is indeed Jocasta. In Greek mythology, Jocasta was the mother of Oedipus and was married to him, though she was initially married to Laius, whose murder at the crossroads set the stage for the tragic events that unfolded. The Sphinx, a creature that posed a riddle to travelers at the gates of Thebes, was a significant challenge. Oedipus ultimately solved the riddle, which led him to confront the Sphinx and save the city, resulting in his marriage to Jocasta. This connection between the riddle, the Sphinx, and Jocasta is a crucial element of the Oedipus myth and illustrates the intertwined fates of its characters.